There is a pleasant, three-bedroom house on a Silver Spring hilltop with a spacious lawn sloping down to the woods. It is five miles from Washington and rents for $165 a month.

In nearby Wheaton, a larger house, with acres of lawn surrounded by woods, has three bedrooms, a dining room, a den, a living room with fireplace and a porch. The rent is a bit higher at $180 a month.

A home in Potomac that sold with five surrounding acres for $82,000 nearly 15 years ago rents today for $236 a month.

And in Prince George's County, a secluded old frame house overlooking a river in Nottingham brings its landlord $140 every four weeks.

These are great deals that do not show up in the "For Rent" ads. These houses are among at least 86 in Montgomery and Prince George's counties that the local park commission rents to its employes.

The publicly financed Maryland-National Capital Park and Planning Commission owns the houses, located in various parks surrounding Washington. But they generally are not available to the public and often are protected by "Do Not Enter" signs and other warnings posted on the roads leading to them.

Following a series of newspaper articles more than three years ago, the commission supposedly reformed its housing program to raise the rents to within 50 or 75 percent of the house's market value.

"We've put it on an extremely businesslike basis," said Charles McGovern, Montgomery's park property manager. "We've hired outside appraisers."

But the appraisals are three years old, and the rents, according to one local broker, don't come close to what the houses would bring on the open market. For example, last April, seven Montgomery County houses were rent-free.

Broker Harold H. Huggins, a Montgomery County landlord-tenant affairs commissioner, said a house matching the description of one the park commission owns in a lovely wooded area of Wheaton Regional Park would normally rent for about $400, perhaps $25 or $50 less "even in the worst shape."

The tenant of that house is Kenneth Ernst, a $21,000-a-year park naturalist who pays $165 a month in rent. Ernst is the son of Montgomery Parks Director Stanton G. Ernst, but the father insists his son "was not hired by me or promoted by me." Kenneth Ernst moved into his house before his father was promoted to his present post.

The park director said that his son's low rent was justified by his work, which sometimes includes feeding animals and opening a nearby nature center for scouts.

McGovern and his Prince George's County counterpart, Lloyd Morris, said the best bargains in houses go to employes or others recommended by local park supervisors.

The low rents are justified, they said, because the tenants often do some additional work in the parks and because the commission pays only for major repairs.

Director Ernst also said preference is given to lower-income employes, although the commission's own records don't support that.

"You hear all the time our employes are $30,000, but we have $8,000 to $10,000 employes," Ernst said. "So when they [get] a house at slightly reduced rentals, they don't think it's all that neat."

But the commission's most recent records show that only one of the 68 Montgomery parks employes living in park houses earns less than $10,000 a year.

The median income for Montgomery County employes living on park property is about $17,000. In Prince George's, where 18 employes live in park houses, the workers' median income is about $16,800.

At least one tenant, division chief Herbert Robinson in Prince George's, makes $35,000 a year and pays $140 a month for his river view house in Nottingham.

"I've lived in park houses for 25 years," Robinson said. "It's just customary in all the systems I've been in. It's one of the benefits given to professionals."

Not all park employes have an equal chance for low-rent houses, and higher ranking officials often get the best deals.

"If it's a Class A house and a division chief said "I want so-and-so in it," it wouldn't matter to me if he owned four other houses and made $60,000," McGovern said.

Class A houses are those priced at 50 percent of the presumed market value. They generally go to employes recommended by their division chiefs, and extra duties sometimes come with them.

Some Class A houses, however, are in the most desirable category because they are considered historic or simply because someone requested that rating.

Houses that don't make Class A are priced at 75 percent of their presumed value and advertised in the commission's newsletter, which is circulated among parks employes.

Lower-income employes are supposed to get preference for Class B houses, but there are numerous exceptions.

One was a five-bedroom house in Rockfille that the commission rated Class B and priced at $475 a month. A prospective tenant - a sergeant in the park police - said the rent was too high, and the commission reclassified the house to lower the rent. When that still proved too high, the rent was lowered again at the request of the officer's supervisor, who wanted him living close to work, McGovern said.

Officials said there are a few cases in which the commission has been unable to find an employe willing to move into a house - usually because it is priced too high - and the commission then offers the house to the public.

Records indicate there are at least two such cases in Montgomery County.

One non-park employe who until recently rented park land is Montgomery's venerable political figure Col. E. Brooke Lee, father of former Gov. Blair Lee III. The colonel, a founder of the park system, rented what McGovern described as 20 or 25 acres of grazing land adjoining the elder Lee's farm.

He paid $160 a year for use of the property.

Asked why a park house is not generally made available to the public, Morris of Prince George's County replied: "Why should it be?

"We know who they are and can trust them," he said of the park employes. "We know these people understand what this operation is about and have a degree of - I don't want to say allegiance to it - but we don't have a labor union here, for example.

"The majority of employes work more hours than they are paid. The employes are pretty satisfied working here. They're treated nicely." CAPTION: Picture 1, This house in Wheaton Regional Park rents for $165 monthly. Similar houses in area normally rent for about $400 a month. By James M. Thresher - The Washington Post; Picture 2, Charles McGovern, left, Stanton G. Ernst oversee Montgomery County parks. By James M. Thresher - The Washington Post