In the pilot episode of 'ER' overworked residents are the heroes of County General Hospital as they make life-and-death decisions on a daily basis. They include Dr. Mark Greene, a married chief resident who's being wooed by a lucrative practice; Dr. Douglas Ross, a charming, womanizing pediatrician who suspects a mother of abusing her young son; the down-to-earth Dr. Susan Lewis who must console a fragile cancer patient; Dr. Peter Benton, an intense surgeon who is forced into performing a delicate surgery he's not prepared for; and John Carter, an inexperienced medical student who bumbles his way through the cauldron of the emergency room. Julianna Margulies stars as Nurse Carol Hathaway, whose personal crisis takes the ER staff by surprise.

In the pilot episode of 'ER' overworked residents are the heroes of County General Hospital as they make life-and-death decisions on a daily basis. They include Dr. Mark Greene, a married chief resident who's being wooed by a lucrative practice; Dr. Douglas Ross, a charming, womanizing pediatrician who suspects a mother of abusing her young son; the down-to-earth Dr. Susan Lewis who must console a fragile cancer patient; Dr. Peter Benton, an intense surgeon who is forced into performing a delicate surgery he's not prepared for; and John Carter, an inexperienced medical student who bumbles his way through the cauldron of the emergency room. Julianna Margulies stars as Nurse Carol Hathaway, whose personal crisis takes the ER staff by surprise.

Carter's first full day finds him saving a patient from cardiac arrest. Later, he treats a co-worker's rash and winds up going home with her. Meanwhile, the ER is inundated with both a tour group and a wedding party suffering from food poisoning from the same German restaurant. When Dr. Greene helps his wife, Jenn, celebrate passing the bar, they get caught having sex in the ER bathroom. Dr. Ross visits a recovering Carol.

Hathaway returns to work and the staff greets her with a surprise welcome back party. Greene treats a domestic violence victim, while Lewis goes on the defensive after a cardiac case goes awry. Benton is shadowed by a patient singing show tunes.

Benton disappoints his brother-in-law Walt when he is too busy to visit their mother. Doug attempts to reconcile with Carol, and also protects a pregnant teen's confidentiality. An older man complaining of chest pains arrives, while another patient's cell phone trips her defibrillator.

A business contractor with a bad heart gathers his family around him in the ER as he prepares for the end. Dr. Ross helps an asthmatic teenage girl when her mother doesn't have the funds. Carter worries that he may have contracted an STD from Liz. Dr. Lewis treats a teenager with alcohol poisoning. Jenn Greene prepares to move to Milwaukee.

The air conditioning quits on the hottest day in October which, coupled with closed ERs in Chicago's other two hospitals, leads to an extremely hectic day. Dr. Ross treats a six-year-old suffering from a cocaine overdose. Ivan Gregor, a liquor store owner, shoots and seriously wounds a young teenager. Susan's immature sister Chloe drops by, wreaking havoc in Susan's life. Doug picks up a pharmaceutical saleswoman, much to Carol's displeasure.

Cater treats a wounded gang member, and later completes his first spinal tap. Ross and Hathaway share a kiss, but Hathaway tells him she's moving in with Oligario. Greene's wife visits, but is soon called back to Milwaukee. The staff throws a surprise birthday party for Lewis, but her drunk sister spoils the festivities.

When Dr. Greene calls in sick to spend the day with his wife, Jennifer, Ross is left in charge for the ER. Dr. Benton learns that he's lost the Starze Fellowship to Dr. Langworthy and Dr. Cvetic exhibits unreasonable behavior. Dr. Carter develops a crush on Dr. Lewis.

Thanksgiving brings unusual patients and family patience. After Carter treats a depressed transvestite for lacerations, the man commits suicide by jumping off the roof of the hospital. In frustration, Carter explodes at Dr. Benton, but later spends Thanksgiving with him. Ross treats a man who was pecked by a turkey, then leaves for a Jamaican vacation. Lewis's alcoholic sister complicates the holiday celebration by announcing that she's pregnant.

When a blizzard brings Chicago to a stand still, the ER staff finds creative ways to pass the time. Just when they are reaching new levels of boredom, a fifteen-car pileup on the expressway wreaks havoc in the ER. With mass casualties, the Chicago Sheriff's department must escort in additional doctors to assist.

First a 6-year-old is revived after almost drowning while ice fishing, then a busload of choir kids seek treatment after a minor bus accident. Meanwhile, Carter treats Santa and assists with a man electrocuted by his Christmas lights. Plus, a boy swallows a Poinsettia leaf and an elderly man is stabbed by people he thought were carolers. Elsewhere, Ross crashes Hathaway's engagement party to tell her he loves her -- and winds up fighting with Taglieri.

After seemingly endless requests, Dr. Benton finally allows Dr. Carter to observe in the O.R. After Dr. Lewis disagrees with Dr. Kayson over the care of a patient, the patient's family sues for malpractice. Meanwhile, Lewis's sister decides to move to Texas with her flaky boyfriend. Dr. Benton and his sister discuss new arrangements for the care of his ailing mother.

Nurse Hathaway is surprised by an injured student's rude behavior, until she learns the student is doing a study on violence in society. Dr. Lewis receives unsolicited advice from doctors Greene and Morgenstern. Dr. Benton is forced to leave an important surgery when his mother wanders off. Carter tries to impress a new, female med student.

Puzzled by a female patient's potentially fatal injuries, Greene discovers that the woman is being abused by her teenage daughter. Lewis and Kayson are brought before the review board regarding the malpractice suit. Later, when Kayson suffers a heart attack, Lewis must treat him. Desperate to avoid putting his mother in a nursing home, Dr. Benton hires physical therapist Jeanie Boulet to care for his mom -- without consulting his sister. Dr. Ross detects cancer in a young boy who arrived with a wrestling injury, and also treats a homeless teen with AIDS.

Dr. Benton is chastised by Nurse Haleh, Nurse Hathaway and his mother's new physical therapist for his condescending attitude. Dr. Morgenstern, impressed by Dr. Greene's performance, offers him an attending position upon completion of his residency -- which doesn't sit well with Greene's out-of-state wife, Jennifer. Meanwhile, a terminal patient asks for Greene's help in ending her life and a poisonous pet snake gets loose in the ER.

On Valentine's Day, a mother leaves her AIDS-stricken adopted, Russian daughter in the ER. After hitting a dog, Officer Grabarsky brings the injured animal in and pleads with the ER docs to save it. Dr. Kayson, a married man, comes on to Lewis. Carter and Chen treat three cheerleaders after eating LSD-laced Valentine's candy. Chen unknowingly eats a piece of the candy, which affects her ability to treat patients.

Both Benton and Greene miss important birthday engagements. Benton, his mother's birthday and Greene, his daughter's. Carter, thinking it's Benton's birthday, organizes a surprise party, but the surprise is his when he discovers the truth. Dr. Ross risks his career when he yells at an abusive parent of a baby girl. Hathaway tries to adopt the Russian girl left in the ER, but Taglieri is against it.

In order to make up for time he took off to care for his mother, Benton works 48 hours straight, which worries Dr. Hicks and has serious repercussions for Benton's mom. It also affects Carter, when Benton becomes even more demanding than normal. Dr. Greene's personal problems go from bad to worse when his wife tells him she may be falling out of love with him. The AIDS hospice turns down Hathaway's request to adopt a Russian teen due to Hathaway's suicide attempt.

Dr. Greene goes all day in solving his patients' problems, until he encounters the case of a pregnant woman suffering from complications that threaten both her life and her unborn baby's. Elsewhere, a teenager is accidentally poisoned by insecticides.

Carter and Chen extend their shifts to experience the ER during a full moon, and they are not disappointed. Greene is so despondent over the breakup of his marriage that Lewis is left to run the ER. Lewis's skills impresses the new ER Chief, Dr. Swift. Patients include nine naked fraternity pledges are brought in with frostbite after a hazing stunt, a drunk man hit by a car, a hiccuping guy who comes out to his fiancee after being diagnosed with HIV.

On Taglieri's recommendation, Benton's mother is released from the ER into a nursing home. After a near-fatal error, Chen contemplates giving up medicine. Diane and Ross continue their relationship. Lewis's sister returns, eight months pregnant and homeless.

Already on bad terms with the new chief, Dr. Swift, Greene refuses to work late and travels to Milwaukee instead. Ross, as a consequence of hitting an abusive parent, is forced to see a psychiatrist. Unable to help his ailing mother, Benton goes above and beyond the call of duty to help save every patient he sees.

As their wedding day rapidly approaches, Hathaway and Taglieri argue over the details and Carol puts off writing her vows. Greene moves to Milwaukee in an attempt to save his marriage, and his deteriorating performance in the ER ires Dr. Swift. Benton agrees to recommend Carter for a surgical sub-internship, although he and other ER coworkers are surprised to learn of Carter's wealthy background. Benton is also surprised by his growing attraction to Jeanie Boulet.

Despite having kicked out her pregnant sister, Lewis winds up delivering Chloe's baby girl in the ER. However, plans for Chloe and the baby to live with Lewis's mother, Cookie, are thwarted when Cookie refuses. Meanwhile, Carter is rejected for the surgical internship after rejecting an ER internship with Greene. Diane asks Ross to move in with her -- which sends a scared Ross into the arms of his former lover, Linda. At the end of a harrowing day, Benton learns that his mother has died, and finds comfort with Jeanie Boulet.

Greene is slapped with a malpractice suit regarding the pregnant woman who die while in labor. Later, Swift offers Greene the attending position. Carter, convinced this is his last day in the ER, slanders Dr. Benton in final evaluations. However, Carter later gets the surgical internship when the first candidate turns it down -- and he also learns that Benton gave him high marks. As the ER crew gathers at the church for Carol Hathaway’s wedding, Carol and Tag both realize that he loves her more than she loves him. The wedding is called off, but the reception goes on anyway.