University of Pittsburgh Medical Center Health System and Highmark Blue Cross/Blue Shield are facing an April 2 deadline in reaching an agreement on a new contract.

With 19 hospital systems, UPMC is the largest healthcare provider in western Pennsylvania while Highmark is the largest health insurance carrier. Both are non-profit organizations based in Pittsburgh. UPMC Horizon, which has hospitals in Greenville and Farrell, is part of the UPMC system.

"We are in the negotiation process with Highmark over our contract with them, which we all hope very much we can resolve in an amicable fashion," said J. Larry Heinike, president and chief executive officer of Horizon.

UPMC's current contract expires June 30 but Heinike said "notice requirements'' call for the two sides to reach an agreement by April 2. He was unsure if the deadline was a regulatory matter or if it was self-imposed by the two parties.

In recent years UPMC and Highmark have quarreled with each other on matters ranging from advertising to hospital merger agreements. UPMC Horizon Health Plan, a for-profit arm of UPMC Horizon, offers health insurance packages and competes head-on with Highmark.

Heinike dismissed talk that UPMC was suggesting it might not accept Highmark insurance payments if an acceptable deal wasn't in hand.

Negotiations were proceeding without rancor, Heinike said.

"I don't think anybody is approaching this with something over somebody's head,'' he said.

A Highmark spokesman didn't immediately return a phone message left on Tuesday.