What is the name of the hospital that merged with Seattle Grace in season 6?

The hospital that merged with Seattle Grace in season 6 was Mercy West Medical Center. The merger brought Mercy West residents and staff into Seattle Grace, creating the combined institution known as Seattle Grace Mercy West Hospital.

The storyline begins after Seattle Grace faces serious financial pressure and administrative upheaval. Rather than operating as entirely separate competitors, the two hospitals combine their staff and resources. The arrival of Mercy West doctors introduces characters including Jackson Avery, April Kepner, Reed Adamson, and Charles Percy.

The merger changes the show’s workplace dynamics. Existing Seattle Grace doctors must compete with unfamiliar colleagues for jobs, surgeries, and authority, while the new residents must adapt to a hospital with its own established hierarchy. The tension becomes especially visible during the early part of season 6.

Grey Sloan Memorial is a later name, not the answer to this question. After the season 8 plane crash and subsequent events, Seattle Grace Mercy West is renamed Grey Sloan Memorial Hospital in memory of Lexie Grey and Mark Sloan.