It is a secluded spot on the edge of a creek and a small woods in the Hillmead section of Bethesda. The other homes, in the neighborhood are neatly kept. The neighbors all are friendly. And to Ahmad and Mary Haeri, it seemed like the perfect place to build the kind of house they had always wanted.

The Haeris completed their home last year. But everything has not turned out quite as they expected. The frequent victims of vandalism, the Haeris never go out anymore without having someone watch over their home. They installed alarms around the property to detect trespassers.

"Our house is e verything we wanted. But if we leave it, we don't know what is going to happen . . . We're just sitting in the house all the time . . . scared togo off." Mary Haeri said.

The Haeris are like many suburban families who settled outside the city hoping to escape the threat of violent crime, only to find that that threat is sometimes replaced by the threat of constant harassment from vandals.

Though they are one of the extreme cases, the Haeris, have found that they have had to change their entire life style because of the vandalism. Their attitude toward their own community has also changed. They have become, in effect, prisoners in their own home.

"I never expected problems in this neighborhood," said Mrs. Haeri, who moved to the wooded secluded Hillmead neighborhood from a more crowded neighborhood in Silver Spring. "The neighborhood seems so quiet. It looks so nice. All the people are nice."

When the Haeris were building their new house, worth double what their old house in Silver Spring cost, vandals come nearly every night. They broke windows, poked holes in the house's siding, stole building materials, and dumped boxes of nails in a creek near the house.

"You don't expect this in an area like Hillmead. But it's no different than living in the middle of the city," Mrs. Haeri said.

The Haeris stopped counting how much the vandalism to their home cost them after a few hundred dolllars. Often they had to pay contractors to do work over again, and eventually the cost ran into thousands of dollars.

Once, the director of a nearby home for problem and home for problem and homeless juveniles learned that some of the home's residents stole building materials from the Haeris, he gave the Ahmad Haeri a check of $75, to replace what was stolen.

"If they stole things I could understand. But this was mostly breaking things. You don't expect that from kids in a good neighborhood. You would think parents would stop them.

"If we knew all this was going to happen, we wouldn't have built our house here," Mrs. Haeri said.

Vandalism is on the rise in most of the area's jurisdictions, according to police statistics, and police in Fairfax and Montgomery counties both re- cently initiated new programs to crack down on the problem.

It is mostly 14-to 18-year-olds "out on a lark" who are responsible for the vandalism and "we can still give most of the credit to teen-age boys," said Lt. Joseph Hancock of the Montgomery County crime prevention section. Most of the teen-ageers prey on families they know in their own neighborhoods.

THe damage may only be a broken flower pot, eggs thrown at a front door, or a mail box knocked over-but more often, the vandalism takes the form of slashed tires, smashtd car windshields and broken house windows. Thus, 60-seconds-worth of vandalism could cost the victim several hundred dollars.

"It's like being nubbled away at by rabbits," said another Hillmead resident, a neighbor of the Haeris who asked not ot be named for fear of reprisal.

"It's just piddly things most of the time. But it can drive you up a wall . . .

You wonder when the first really serious (vandalism) is going to happen. You wonder when somebody is really going to get hurt."

Most vandalism victims say what bothers them the most is not the expense, or the time it takes to make the repairs, but the fact that the vandals seem to attack for no particular reason at all-and really get caught.

Margaret Baganz, for example, who lives in an exclusive Potomac neighborhood, is a 4-time vandalism victim, has had a pipe bomb and fire crackers set off on her front lawn, and about three weeks ago, someone ignited some rags in her car and etched a swastika on the side of the car door.

Yet, police have made no arrests in any of the incidents, and Mrs. Baganz is at a loss to provide any leads for suspects. After the last attack, Mrs. Baganz told police she plans to sell her house.

She declined to be interviewed for this article on the advice of the Montgomery County police officer investigating the most recent vandalism at her home.

The closure rate for vandalism is about one out of every 12 cases, according to Hancock. The reason is that there are usually no witness to a vandalism and in some cases where the vandals are known to be neighborhood youths, the victims are reluctant to press charges and risk reprisal. Some victims do not want to create trouble in the neighborhood, Hancock said.

Most of the frustrated victims of vandalism say they feel the police don't do enough to patrol their neighborhoods. Police say that the problem can be curbed only if residents watch out for one another and report the incidents they see to police-something police say is not done enough.

"I think a lot of this (reluctance to get involved in a community effort) is caused by the police approach," said Jerrold Harvey, a vandalism victim from the Olney Mill section in Montgomery. "When they came to check out my (vandalism) complaint, they asked all kinds of questions about me . . . I finally said. "Hey wait a minute. I'm not the criminal. What's all this jazzasking questions about me?"

Hancock said the Montgemery County crime prevention unit is willing to hold community meetings in any neighborhood, as it did recently in Olney Mill, to discuss what can be done to curb vandalism.

But, said one victim from Hillmead. "The more you complain the more it gets worse. You try being a contemporary adult and think the thing to do is talk to the kids. But it doesn't work."