The sixth season of the American fictional drama television series ER first aired on September 30, 1999, and concluded on May 18, 2000.
In the first major cast change in ER, the sixth season sees the addition of four new characters: Dr. Luka Kovač; nurse, later third-year medical student, Abby Lockhart; Dr. Cleo Finch; and Dr. Dave Malucci.
In addition Croatian doctor Luka Kovač joins the team and struggles to gain the respect and trust from his new colleagues in the ER.
This season saw the exits of Julianna Margulies, Gloria Reuben and Kellie Martin as series regulars.
Michael Salmunovich returned as a co-producer and Teresa Salamunovich joined the crew, initially as a production co-ordinator but was promoted to associate producer mid-season.
Returning directors were Lesli Linka Glatter, Félix Enríquez Alcalá, Christopher Misiano, David Nutter, and Steve De Jarnatt.
New directors include Ken Kwapis, Marita Grabiak, medical consultant Fred Einesman, Kevin Hooks, and Peter Markle.
Weaver may be head of the ER, but Greene has his own ideas about how to handle situations and after his mother's death the two of them have their worst conflict on the job yet.
An elderly woman bids farewell to her dying husband, and Lawrence admits he is in the early stages of Alzheimer's, and that his distinguished career is over.
Lawrence departs (but not before saving a life), and Kovač comes aboard full time after earning Weaver's respect.
Corday discovers her new trauma patient is a rapist and takes extreme measures to find his latest victim.
Benton and Anspaugh repair the damage to Carter while in another operating room, Corday and Romano fail to save Lucy.
Touched by a family tragedy at the ER – a dying DNR cancer patient whom she hopes to keep alive just long enough for her young children to say their goodbyes – Hathaway realizes she must see Ross.
Abby is supervised by Malucci on a case that leads Corday to tell him that no one at County thinks he is any good at his job.
Corday returns the necklace to Greene, who then gives it to his daughter Rachel while showing her her late grandfather's favorite Chicago lakeside spot.