At least three Bethesda teen-agers were hospitalized and two more became ill but did not need hospitalization after inhaling an experimental drug that police said was stolen Sunday from the National Institutes of Health.

D.C. police are also investigating three cases in the District in which youths have been hospitalized with similar symptoms to see if there is a connection to the Bethesda cases.

Police said the drug is a white powdery substance, believed to be a form of cocaine or codeine. Narcotics investigators believe the number of youths who may have come in contact with the drug is probably far greater than those who were hospitalized.

Police said the drug was stolen Sunday from the Bethesda-based research facility by a youth who is a volunteer worker there. The youth has been charged with distribution of cocaine.

The exact contends of the drug are unknown, but police said it was used in an experiment 20 or 30 years ago conducted by a researcher who is no longer at NIH and whose whereabouts is unknown.

The drug was left "just sitting on a shelf" one investigator said. Four or five vials of the drug were taken, although the exact quantity distributed is unknown, police said.

Youths began showing up at Suburban Hospital in Bethesda on Tuesday, suffering from hallucinations and blurred vision, according to police. Police said some of the youths tried to attack hospital personnel. They had apparently sniffed the drug, police said.

On Wednesday night, two youths were hospitalized in the District who were suffering from the same symptoms, Montgomery County police said. At least one other case has been identified since then, while District narcotics officers are continuing to check the city's hospitals.

Montgomery County police have requested that youths who have a sample of the drug bring it to a police station so it can be analyzed. They have agreed to press no charges against youths who help in the investigation.

In asking for help in the investigation, one officer said, "We don't know what this (drug) is. All we know is that these kids have been in the hospital for quite a while now. We don't know what the physical repercussions (of the drug) will be . . we're not out to look people up."

Investigation of an unrelated burglary led police to obtain information about the drug theft at NIH, police said.

Police said all of the youths in the Bethesda area who became ill were acquaintances of the youth charged with distributing the drug.