For months, residents of Malcolm, Md., an isolated farming community in northeastern Charles County, have been complaining to authorities about increasingly brazen drug traffic there, county officials say.

The residents told Maryland state police that they were being harassed on their way home at night by persons trying to sell them cocaine, marijuana and PCP at the community's main intersection, about three miles from the Prince George's County line.

They also complained to police about noisy crowds that gathered each weekend in the parking lot outside the Birdland Bar in Malcolm, and said they were afraid to go near the small shopping strip that is the community's main commercial area.

After a 15-month undercover investigation, 75 Maryland troopers from six counties converged on the community of about 200 residents in a predawn raid Sunday and arrested seven men they allege are part of a drug distribution ring in Southern Maryland. The men are residents of Charles, Prince George's and St. Mary's counties, police said.

Two women were arrested in Lexington Park, Md., at the same time, and warrants for eight other persons are still outstanding, said a state police spokesman, First Sgt. William Tower. Those arrested were charged with possession or intent to distribute illegal drugs, he said.

Tower said the raid was one of the largest in Maryland in recent months and represents a "new, tough attitude toward drug dealers . . . . We want folks to know we're not going to let drug dealers take over a town."

"We've had assaults down there, and knifings, and one of our officers got hit in the face with a bottle while he was investigating a car accident," said Lt. Jesse N. Graybill, commander of the state police barracks in Waldorf, Md.

"I've worked in the county for 22 years and that area has been a sore that has festered for years. It's a chronic problem area with blatant drug dealing that leads to a lot of other things," he said.

Charles E. Jackson, director of public information for the state police, said that in recent years, Malcolm has been "a drug-plagued area."

The Charles County Sheriff's Department has made 18 drug-related arrests in the community since January 1984, said Sgt. Casey McDevitt, a department spokesman.

Tower said it was common to see "several hundred people congregating in the parking lot outside of the Birdland Bar. That was the center of things . . . . Law-abiding citizens were upset about what was happening."

Howard Bernard Wills, the owner of the Birdland Bar, is currently serving a prison sentence for a drug conviction, McDevitt said.

Graybill said a large contingent of troopers was dispatched for this weekend's raid, along with a tactical weapons team, "because every time we've gone down there, we've had trouble: tires slashed on patrol cars, windows smashed and troopers roughed up."

In another raid, on an abandoned dairy farm in rural Cecil County this weekend, state police arrested three persons and confiscated four gallons of methamphetamine, a central nervous system stimulant known on the streets as "the poor man's cocaine."

Tower said federal Drug Enforcement Administration chemists said there was enough material to produce 400,000 doses with a street value of at least $2 million.