Premier Medical Network, a managed care organization that contracts with hospitals and physicians to offer a cost-effective health care delivery system to Utah employers, has signed a contract with Mrs. Fields Cookies in Park City.

The contract covers 130 workers in Mrs. Fields' corporate office. Mass Mutual Insurance Co. will pay the claims.Gary Takagi, director of corporate taxation/em-ployee benefits for Mrs. Fields, said he expects to see a decrease in the average claim cost by utilizing PMN's managed care system. "This program should help us gain control over our medical costs," he said.

PMN has enrollment of 50,420, a 17 percent increase over the 41,790 enrollees it had at the end of 1990, according to Kevin Potts, sales and marketing director.