Mercy West Medical Center is the former rival hospital to Seattle Grace. Like Seattle Grace, it is deemed one of the best hostpitals in Washington untill Mercy West and Seattle Grace merged to form Seattle Grace Mercy West.
Dr. Hahn and Dr. Burke are seen arguing over which doctor will be harvesting a heart from a Mercy West patient. Episode: '17 seconds'
On Thanksgiving, Dr. Kent worked at an understaffed Seattle Grace. He was seen to be rude to Dr. Bailey demanding that she just went to fetch the resedent they called 'the Nazi' Unbeknown to the fact he was talking to her. Episode: 'Thanks for the Memories'
An intern from Mercy West, Dr. Marshall, was admitted after causing a car accident. Episode: 'Damage Case'
Dr. O'Malley applied to become a resident at Mercy West Medical Centre. He was accepted pending the result of his intern exam; he failed the examination and returned to work at Seattle Grace
Due to Dr. Webber not being able to promote her to attending, Dr. Torres took a job at Mercy West.
Dr. Webber was admitted to Mercy West after being involved in an accident; he had Dr. McKee as his doctor.
Although there were roumers that Dr. Webber would be leaving to take a place on the staff at Mercy West Medical Centre, he later reveled that Mercy West and Seattle Grace would be merging to form Seattle Grace Mercy West hostpital.