Some 50 elderly tenants at the Parkside condominium complex in Bethesda won a reprieve last week from rent increases of up to 90 percent, after the developer and the Montgomery County government reached agreement on subsidies for the increases.

Under the agreement, about 35 tenants older than 62 will receive help from the county's Tenant Displacement Aid Fund to cover part of the rent increases, which increased by $300 a month in some cases.

In addition, the developer, Gary Nordheimer, agreed that for the next nine months, he will pay 50 percent of the increase over the present rent and the county subsidy.

A full-time employe will be designated by the developer to help the elderly tenants in relocating from the complex at 10522 Montrose Ave. as part of the agreement.

So far, the county's Division of Elder Affairs and the Office of Consumer Affairs have had little luck finding accommodations suitable for the elderly tenants, some of whom have lived at Parkside for 20 years.

The developer will pay each tenant $750 within 10 days after a tenant moves out, under the terms of that agreement.

In a letter to County Executive Charles W. Gilchrist, outlining the agreement, consumer affairs program manager Joe Giloley wrote: "The arrangement that has been made concerning the imposition of these rent increases at Parkside is only a stop-gap measure and in no way addresses the long-range problem of securing a stable living environment for many of the lower-income senior tenants who are presently caught in the rent squeeze at Parkside."

The Parkside case illustrates the county's shortage of low-income housing for the elderly and minorities.

The Parkside case also underscores the skyrocketing rental market in areas of the county close to Washington or near projected Metrorail stations.

The developer at Parkside claimed the high rent increases were needed to bring his property up to the value of other rents in the area, which had been pushed up with the scheduled opening of the Grosvenor Metro stop.

Nordheimer complied with the letter of the law since the conversion of Parkside to condominiums began in 1980, according to Montgomery consumer officials. He offered three-year leases to the elderly--longer than required by law at that time--and instituted one small rent increase during the three years. Those leases expired in July.

Since the conversion began, the state and the county have placed tough new restrictions on condominium conversions, requiring developers to set aside 20 percent of the units in a building to elderly tenants. Those new restrictions came too late for the Parkside tenants because the conversion there began before the new law took effect.