|No. of episodes||22|
|Original run||September 30, 1999 – May 18, 2000|
|DVD release||December 19, 2006|
- Main article: Season six crew
- Michael Crichton - Executive Producer
- John Wells - Executive Producer, Writer
- Lydia Woodward - Co-executive Producer, Writer
Cast and characters
|Anthony Edwards||Dr. Mark Greene||Emergency Medicine Attending|
|Noah Wyle||Dr. John Carter||Emergency Medicine Resident (Year 2)|
|Julianna Margulies||Nurse Carol Hathaway||ER Head Nurse|
|Gloria Reuben||Jeanie Boulet||Physician Assistant|
|Laura Innes||Dr. Kerry Weaver||Chief of Emergency Medicine|
|Alex Kingston||Dr. Elizabeth Corday||Surgical Intern|
|Kellie Martin||Lucy Knight||Medical Student|
|Paul McCrane||Robert Romano||Chief of Surgery / Chief of Staff|
|Goran Višnjić||Dr. Luka Kovac||Emergency Medicine Attending|
|Maura Tierney||Abby Lockhart||Obstetrics Nurse / Medical Student|
|Erik Palladino||Dr. Dave Malucci||Emergency Medicine Resident (Year 1)|
|Michael Michele||Dr. Cleo Finch||Emergency Medicine and Pediatric Resident (Year 2)|
|Ming-Na||Dr. Jing-Mei Chen||Emergency Medicine Resident (Year 2)|
|Eriq La Salle||Dr. Peter Benton||Surgical Emergency Trauma Fellow|
Four new characters are introduced in the sixth season: Dr. Luka Kovač, OB nurse\third-year medical student Abby Lockhart, second year pediatric resident Dr. Cleo Finch and second year resident, Dr. Dave Malucci.
Mark copes with the loss of his parents and grows close to Corday.
Jeanie marries police officer Reggie Moore and becomes a foster parent to an HIV-positive infant, Carlos. She leaves County in the episode The Peace of Wild Things to care for Carlos full-time.
Peter gets into a custody dispute with Carla over Reese when Carla and her new husband, Roger plan to move to Germany for Roger's job, but in the end, they don't move after all.
Carol give birth to twin daughters Tess & Kate on Thanksgiving and struggles with single parenthood. Although she grows close to Luka, she eventually leaves County and moves to Seattle to be with Doug.
OB nurse Abby (who helped Carol deliver one of her twin daughters) appears in the ER as a third-year medical student. Things take a turn for the worse when Lucy and Carter are attacked and stabbed by a psychotic patient. Although the team battle bravely, they are unable to save Lucy, who dies from her injuries, leaving Carter devastated.
Carter later develops an addiction to pain medication which forces his colleagues to do an intervention. Although resistent at first, the season finale shows Carter heading off to rehab with Benton accompanying him.
- Main article: Episodes