Two years ago, groups of men, 20 and 30 strong, ruled the parking lots of Prince George's County's Kent Village Apartments, selling drugs so brazenly that their shouted offers to customers could be heard half a block away.

One resident of the Landover area complex said she was so fearful of the drug trade and its attendant violence that she rearranged her bedroom furniture, placing a tall dresser in front of the window to block possible bullets. Another woman said she refused to empty the trash alone, even during the day.

Today, the streets surrounding Kent Village are empty of all but infrequent pedestrians and children returning from school. The only reminders of the once-flourishing open-air drug market are the banners strung across streets around the complex near Vermont Street and West Forest Road.

"We, the residents of Kent Village Apartments, are taking back our community from drugs," one banner proclaims in red block letters.

Elsewhere, in more than a dozen neighborhoods across Prince George's -- the suburban Washington jurisdiction hit hardest by the crack cocaine epidemic and plagued by the highest homicide rate outside the District -- more than half the open-air drug markets have diminished and in some cases vanished during the last year. Narcotics officers said that of the busiest 25 open-air markets identified in 1988 and 1989, about nine are still obviously active.

"I'd like to think that we've turned the corner on the drug problem," said Maj. Larry Bowman, commander of the Narcotics Enforcement Division. "We're just not seeing as many drugs out there as we did in the last year, year and a half."

Certainly, crack cocaine can still be bought in Prince George's. The homicide rate remains near the record pace set last year, though police officials say the percentage of drug-related homicides is down by a third.

Prince George's police added a 20-member Street Narcotics Unit two years ago to tackle the open-air markets. Almost nightly, teams of undercover officers bought drugs, then raided markets to arrest the dealers. Frequently, police selling fake cocaine posed as dealers to arrest unsuspecting buyers.

The attack on the buyers further disrupted the markets and sowed suspicion among dealers and customers, police say. In addition, residents have joined police, becoming a potent weapon in the war against drugs.

"The police can't do it all," said Tonda Brown, manager of the 810-unit Kent Village complex. "We learned that a long time ago, which is why, we, the management and the residents, decided that we were going to start fighting the battle ourselves."

A sprawling four-block area of the Kentland section of Landover, Kent Village was home two years ago to one of the county's worst open-air drug markets. "Two years ago, I wouldn't let the children I baby-sit for go outside," said Eleanor Cannatella, a Kent Village resident. "Now, it's beautiful. So peaceful."

Members of the Street Narcotics Unit and patrol Action Teams concentrated efforts for several months on Kent Village and other areas of Landover, clearing dealers away from the apartments, the nearby 25-Hour Store on Dodge Park Road and Dodge Plaza shopping center as well.

In addition, Kent Village management organized a group of approximately 70 residents, who, armed only with two-way radios and sneakers for a quick getaway, walk nightly through the maze of garden town houses and low-slung brick apartment buildings, reporting drug dealing when they see it, managers said.

The Guardian Angels also patrolled the complex for a time.

Since the community patrols started, the number of calls to 911 has dropped by more than half, Brown said. Even more dramatic, the number of complaints of drug activity has decreased from a high of 108 calls in June 1989 to an average of five calls a month since the first of this year, according to police statistics.

"What we've done . . . is just move the drug dealers on to another area," said Ron Frank, vice president of Southern Management Corp., which owns Kent Village.

In neighborhoods where citizen apathy is high, drug trafficking is still intense, residents say, despite police efforts.

Some of the county's worst markets two years ago -- Belle Haven Drive in Palmer Park, 14th Avenue and Kanawha Street in Langley Park, Capital View Drive and Nalley Road in the Landover area and Sheriff Road in Seat Pleasant -- still are among the most troublesome, police say.