Five hundred applicants are trying for rooms in the first 87 units of the Mission Park Housing Development, an apartment complex built primarily to accommodate residents displaced from the Med School area by University expansion

The first group of apartments will be ready for occupancy in January, and other units will follow in the next few months.

"I'm very happy to see the development under way--there were long periods when we didn't even know when it would be a reality," a medical area tenant group official said yesterday.

The group, Roxbury Tenants of Harvard (RTH), strongly opposed the University's construction of a power plant in the area when Harvard officials announced plans for the plant in 1969.

The tenant group later backed down, after Harvard helped to obtain financial backing for the Mission Park complex.

Flynn House, the building that houses the development's 87 "senior citizen units," began to accept tenant applications Monday.

A committee that includes RTH representatives will screen applicants for the housing units, Donald C. Moulton, assistant vice president for community affairs, said yesterday.

The development will offer federally-subsized low and moderate-income housing, as well as market-value rentals, Moulton added.

An RTH official said yesterday "one of the biggest disappointments" of the development is that market value rents are too high for many people whose incomes make them ineligible for government aid.

This should not, however, affect most of the displaced tenants, many of whom belong to low- and moderate-income groups that qualify for subsidized housing.