The pilot for the popular TV series is set during 24 frantic hours in the lives of a group of doctors, nurses, and staff members of a busy emergency room at a Chicago hospital. They deal with the seemingly endless casualties that stumble into their place of employment. The central characters are the chief resident and family man Dr. Mark Greene, who is considering a job in private practice due to pressure from his demanding law student wife Jennifer; outgoing Dr. Doug Ross, who deals with cases in his own personal way; straight-arrow Dr. Susan Lewis, trying to get by another long 36-hour shift; inexperienced third-year med student John Carter; cocky surgical resident Dr. Peter Benton; and troubled chief nurse Carol Hathaway.

Mark's wife arrives in the ER with the news that she has passed her bar exams but several members of the staff interrupt their intimate celebration. Greene treats an elderly woman whose husband isn't ready to let her go. It's been eight weeks since Hathaway's attempted suicide, but Doug Ross has yet to bring himself to visit the woman he went out with for two years. Susan Lewis saves a newborn who is brought into the ER choking. She also argues with the psychiatric attending who refuses to admit a patient suffering from dementia. Carter finds himself having to care for a group of German tourists who are suffering from food poisoning. He also treats a young flirt with a rash. Benton treats a recent surgery patient and finds his correct diagnosis overturned by the man's physician. Susan Lewis treats a family struck by a drunk driver. The husband and daughter will survive but there is little hope for the woman. The drunk driver is also brought in suffering from only a few scratches.

Mark Greene's wife Jen gets a position clerking with a Federal judge. Unfortunately, it's in Milwaukee, 2 hours away and she wants Mark to look for a job there. Greene and Susan Lewis treat Samuel Gasner, a man who has been waiting for a heart transplant and who will not survive the night unless a donor can be found. John Carter is worried that his latest paramour may have left him with a souvenir of their sexual encounter. Doug Ross treats a young girl suffering from severe asthma but whose mother can't afford her medication. Benton treats Ivan the liquor store owner who is shot for the third time in as many weeks.

The realities of the ER may be too much for a child, but circumstances force Greene to bring his daughter Rachel with him on a day when the outdoor temperature tops 100 degrees and the air-conditioning doesn't work. Benton and Langworthy try in vain to save a boy shot in self-defense. Meanwhile, Lewis's broke sister, Chloe, steals Lewis's TV and VCR. After Ross crosses the line with Hathaway and Taglieri, Hathaway slugs Ross.

It's a day of birthdays. Peter Benton's mother is celebrating a birthday and he tries desperately to find someone to cover his shift. He makes a choice however when Dr. Hicks suggests that he's been absent too often and may wish to consider a leave of absence until his mother's situation is resolved. Carter thinks it's Benton birthday and has a surprise for him. Mark Greene's daughter is also having a birthday but he misses that due to an emergency at the hospital. An elderly, solitary man in the final stages of cancer arrives in the ER on his birthday. Carol Hathaway suggests to her fiancé that they adopt little Tatiana, the AIDS patient abandoned in the ER. Ross has to deal with a young child who was kicked out of a window.

Greene finds his marriage falling apart and is concerned at how little time he's spending with his daughter. He also treats an eight week old child with a heart murmur who requires surgery. Susan tries to get her pregnant sister Chloe to take her pregnancy seriously, but her head isn't quite into it. Benton tries desperately to find a surgeon who will operate on a 16 year-old with a severe brain aneurysm that could burst at any time. He's also concerned at his mother's care and is growing ever more attracted to Jeanie Boulet. Doug Ross' commitment to Diane Leeds gets more serious when he agrees to be an assistant coach for her son's little league baseball team.

Doug Ross and Nurse Hathaway treat a girls' basketball team from a local catholic school for meningitis. Their teachers also need to be tested but one of them confides in Hathaway that she may have a particular problem. Green and the Chief of Staff have a disagreement in the middle of a procedure. With the wedding only two weeks away, Tag and Carol Hathaway have to deal with all of the final preparations, not the least of which is writing their own marriage vows. Susan deals with a suicide victim who is using emotional blackmail to keep his girlfriend from leaving him. Susan reaches the breaking point with her sister Chloe and tells her she has to move out.

It's Carter's last day in the ER and finally fed up with Dr. Benton's apparent indifference, rejoices when he learns that he gets to write an appraisal on him. He subsequently regrets his negative input when he gets offered the surgical sub-internship he'd hoped for and learns that Benton gave him a glowing appraisal. He also spends a good part of the day with young leukemia victim who is fed up with life. Benton and Jeanie Boulet's relationship reaches a crossroads. Mark Greene is offered an attending position at the hospital but also learns that he is being sued for malpractice over his handling of the Jodi O'Brien case. The big day for Carol Hathaway and Tag is here but doubts creep in and one of them gets left standing at the altar.

Jennifer and Rachel have been involved in a car accident and Mark rushes to Milwaukee where they're in the hospital.

Benton has to attend a banquet at Vucelich's home and asks Jeanie to go with him. Mark hesitates to tell Rachel about the divorce.

Mark and Kerry have to create a policy regarding HIV-positive employees, which leads to gossip amongst the nurses.

Race relations become an issue in the ER when Mark Greene treats two injured teenagers, one black and the other white, and assumes the black kid was a drug dealer. It turns the white kid was the drug dealer and the black kid is a high school basketball star and an innocent bystander. When the black student's older brother confronts him, he begins to question his own impartiality. Carol Hathaway helps a young woman who was drugged with Rohipnol and raped. Benton gets an interesting offer from Dr. Hicks. He also learns that Carla Reece has been admitted to the hospital. Dr. Carter treats a woman with a serious condition but he seems to be the only one who sees it. Mark Greene's daughter ends up spending the day in the ER when her mom has to rush to Florida to deal with a family emergency.

Benton tries to find out if everything's OK with Carla's baby. Carter tries to get a man operated, despite the fact Anspaugh thinks he will die no matter what.

Benton takes a day off to help Carla. Carter finds out Edson falsified a chart.

Jeanie believes she's been fired because she has HIV and fights her dismissal.

Third-year med student Lucy Knight reports to the ER for the first day of her rotation. Greene takes a paternal interest in her, helping her get acquainted, but she gets off to a bad start with the irritable Carter. The rest of the day finds her informing a wife of her husband's terminal condition, comforting a pregnant woman, getting locked on the roof and trying to figure out Weaver's "Tour on Tape."

To save rent money, Carter lives in a medical student dormitory as a resident advisor. While visiting Corday at her apartment, Benton meets her father.

Benton performs dangerous surgery on a bomb-carrying man who was shot at a factory. Dr. Ross receives some good news that Dr. Weaver doesn't embrace, but she has no recourse. Rachel encourages Dr. Greene to help a horse that is in pain. Jeanie Boulet returns from her vacation.

It's Halloween in the ER, and the medical students throw a party; as a result, Carter decides that Lucy isn't mature enough to take responsibilities. A candidate for the ER Chief position arrives from New York and drives home disappointment for Kerry. Mark screws up when he doesn't recognize a homeless schizophrenic woman is pregnant before treating her. Benton treats Corday to a fun Halloween.

After his mother's funeral, Dr. Greene comforts his father (JOHN CULLUM) in San Diego. In Chicago, Romano surprises Corday by appointing her associate chief of surgery. Corday treats Elaine, Carter's lover, for breast cancer.

On Thanksgiving Day Carol goes into labor. She's able to get to the ER only thanks to Luka's help. She delivers the first baby in the ER, but the second causes some trouble. Greene leaves Elizabeth to deal with his father and daughter, as he rushes to assist Carol.

Greene prepares to bury his father. Chen worries about Carter's mood swings. After witnessing the interaction between a dying woman and her family, Hathaway realizes she wants her family together and flies to Seattle to join Ross.