More than 100 misdemeanor drug cases, including some in which the defendants have pleaded guilty, have been dismissed in the District in the past six months because of lengthy delays in obtaining drug analysis results, and police and prosecutors say the dismissals are putting a serious crimp in their battle against crime.

A high-ranking assistant U.S. attorney and several prosecutors who handle drug cases estimated that an average of a dozen, and often many more, misdemeanor cases have been dismissed each week for the past several months because chemical analysis reports had not been received from the federal Drug Enforcement Administration.

Last Wednesday, for example, three of five misdemeanor drug cases scheduled in a single courtroom were dismissed by D.C. Superior Court Judge Noel A. Kramer because the necessary analyses were not ready.

In addition, prosecutors expected a fourth case to be dismissed because of a missing lab report, but the defendant did not show up and the trial was postponed. The reports would represent the key trial evidence as to whether a substance was an illegal drug.

"Cases are getting dropped so often, I don't take it personally anymore," said a prosecutor, leafing through a sheaf of cases that had been dismissed in the past couple of weeks, including one in which a defendant had pleaded guilty contingent on the drug testing results. "Looking on the bright side, it can't get any worse; it can only get better."

Prosecutors stressed that drug cases involving more serious felony charges have not been dismissed, although they have experienced some delays with the DEA.

DEA officials conceded that their mid-Atlantic laboratory has a backlog of about 1,200 drug samples. They blamed the growing problem on the failure of federal funding levels to keep pace with the skyrocketing number of drug cases being brought here since former president Nixon ordered federal agencies to perform drug analyses for the District police agencies.

"We are trying the best we can, but we keep falling further behind," said Marc Cunningham, DEA's chief laboratory chemist. " . . . What we're doing is crisis management. That's not proper and adequate support of the criminal justice system, and that's what we're here for."

Prosecutors said that felony cases, which involve sale or distribution of drugs other than marijuana, have not been dismissed largely because the period between arrest and trial is longer.

But more important, they said, misdemeanor charges, which are becoming more difficult to prosecute because of the DEA backlog, often belie a defendant's criminal behavior.

They cited a heroin possession case against a suspected major dealer, believed to employ as many as a dozen persons, that was dismissed this summer because there was no DEA report.

"It was the first time in a long time that the police had found a major dealer with drugs on him," said the prosecutor involved in the case. "Although it was only a misdemeanor, the police looked on the charge as a way to get this guy off the street for a while."

The cases are usually "dismissed without prejudice," which allows prosecutors to charge the defendant again if a report ultimately confirms that the substance was an illicit drug. But prosecutors said few charges are lodged a second time. The government's cost of trying a misdemeanor drug case -- which usually carries a maximum one-year jail term -- is more than $1,000, they said.

Officials said they have not decided whether to charge the suspected dealer again.

Prosecutors said they are experiencing a "tidal wave" of drug cases this year, and expect the number to exceed the more than 9,400 cases in 1984. The number of cases last year was more than double the drug cases here five years earlier. But funding levels for state and local work at the DEA's chemistry lab has remained about constant for the past several years, said Richard S. Frank, chief of the DEA's forensic science laboratory.

U.S. Attorney Joseph E. diGenova said during the weekend that he had not been able to determine how many drug cases have been dismissed. A high-ranking prosecutor in diGenova's office said the number could be as high as several hundred.

"But the fact is there have been delays, and DEA needs to do something about them," diGenova said.

As a result of the problem, he said, Congress is expected in the next couple of weeks to grant a Justice Department request for more DEA funding. When drug crimes are up, he said, all crime increases.

DiGenova said the link between drug use and crime is underscored by the fact that nearly 70 percent of the persons arrested for crimes this year in the District have shown traces of drugs in their urine at the time of their arrest.

"All your major crimes are being committed by people directly or indirectly involved with drugs," said a D.C. police narcotics officer. " . . . When you have a chance to pull these people off the street you have a chance to reduce burglaries, armed robberies."

Cunningham of the DEA said his lab receives about 1,000 requests a month, including about 600 from the District and varying numbers of requests each month for federal drug cases in Maryland, Virginia and West Virginia.

Testing for drugs, Cunningham explained, is a complex, time-consuming process, with each analysis requiring about 3 1/2 hours of "hands-on work" by a chemist. He said the laboratory's 26 chemists spend about half the day completing analyses and are able to perform only about 35 cases during that time.

About a year ago, prosecutors said, drug results were usually returned in about 16 working days, but that turnaround time has stretched to several weeks, and to months in many cases.

Judges initially tolerated delays but, "We are now getting wiped out every day on those cases," said a prosecutor who leads a misdemeanor drug case prosecution team.

Judge Fred B. Ugast, who heads the criminal division at D.C. Superior Court, said the continuous delays in trials have caused "calendars that are already quite heavy to become even heavier."

Although the majority of these problems arise in misdemeanor cases, serious delays in felony cases have occurred. This past summer, D.C. Superior Court Judge Virginia L. Riley issued a bench warrant for the arrest of an unidentified DEA chemist. Her action followed repeated requests by the government to continue sentencing because no drug report was available nearly four months after a defendant pleaded guilty to possession of a narcotic with intent to distribute, a felony charge that carried a mandatory prison sentence.

"It gives me the greatest concern . . . ," Riley said in August when Cunningham appeared at a hearing in response to the issuance of the bench warrant. At that point, the report had been received and the defendant sentenced.

"It's very wasteful of court time and also of attorney time," the judge said. "The overall effect is terribly costly."

In another case, a defendant pleaded guilty in May to possession of PCP, but after repeated court appearances and nine requests for the drug report the case was dismissed in August. Several days later, the drug analysis was returned. The results were positive.

Prosecutors made the atypical decision to charge the defendant again after the prosecutor involved complained to supervisors. "I rarely urge that we rebring a case," said this prosecutor, "but this seemed so ludicrous."

According to prosecutors, some defense lawyers are beginning to ask for quick trials, which can occur as soon as six weeks after arrest, for clients charged with misdemeanor drug counts. This is done in hopes that the drug report will not be ready and the charges could be dismissed, prosecutors said.

A delay in the reporting of drug tests does not always work in a defendant's favor. For instance, Moshood Alatishe was held in jail for three months without bond before it was learned that no evidence of narcotics was discovered in the powder seized during a raid at his home. In this U.S. District Court case, the test apparently was completed but the results were not sent to the U.S. attorney's office for more than a month becaue of a typing backlog.

As a result of the Alatishe case, the DEA has asked to be notified when a defendant is being held in jail pending the test results.

"It is simply unacceptable," said a high-ranking prosecutor. "Here we have the great Reagan war on drug abuse nationally and we have our own little problem right here in the nation's capital. We've made the arrests and the federal government is not coughing up the resources."