Sun Healthcare Group Inc. will acquire Harborside Healthcare Corp. from Investcorp International, an investment firm, for approximately $350 million in cash.

As part of the purchase, Irvine, CA-based Sun Healthcare also will refinance or assume Harborside’s net debt of approximately $275 million. Boston-based Harborside operates 76 facilities, 53 of which are owned. The acquisition will increase Sun Healthcare’s owned properties from 30 to 83.

The transaction is expected to close in the first half of 2007, subject to regulatory and other approvals.