For local heroin addicts, "New Jack Swing" isn't the name of a dance, a hairstyle, a movie or a rap song.

It's one of several names for a potent heroin that is cut with morphine. Addicts love it because of the extended high it gives. But it also increases the chances of overdose.

"If you are an older junkie, you can die," said Baltimore Eastern District Officer Edward C. Bochniak. "The dangerous part about this is that these addicts have no idea what they're getting in the bag. They just fire it up and shoot it in their arms, then they have an overdose. What they're playing is an extreme game of Russian roulette."

"New Jack Swing," "Parachute," "Body Bag," "Supreme," "Top Choice" -- these are the brand names for the high-purity heroin that brings droves of addicts to any open-air drug market where they are sold. These brands first hit the streets 18 months ago.

Police drug enforcement officers said the popularity of these brands is an ominous indicator that addicts have pushed aside fears of overdose, AIDS and other diseases and developed an appetite for stronger heroin. Police believe several addicts have died from overdoses on "New Jack Swing" and other competing brands of high-purity heroin.

"New Jack Swing," which bears the hip-hop name of its city of origin -- New York City -- is a packaged brand and is about 4.9 percent pure heroin, more than twice the purity normally used by heroin addicts.

Usually cut with morphine, but sometimes embalming fluid "New Jack Swing" gives addicts a high that lasts anywhere from six to eight hours. Already packaged, it also eliminates the need for most heroin addicts to recut the $10 and $60 glassine bags of heroin sold on the street.

It's a high-stakes game for the state's estimated 50,000 heroin addicts, more than half of whom live in Baltimore. They depend on traffickers to come up with a brand of heroin strong enough to keep them high for hours but not so strong that it kills them. It's an exercise in blind faith practiced several times a day by thousands of addicts.

"Any time anybody can make a batch of 10 percent, you'll have a street full of dead junkies," said Sgt. John P. Sieracki, head of the Eastern District's drug enforcement unit.

Despite the risks, "New Jack Swing" is fast becoming the No. 1 choice with addicts.

"You ain't in heaven, but that's how you feel," said one East Baltimore heroin addict who supplements her $500-a-day habit JTC with free samples of "New Jack Swing" a local drug organization gives her in exchange for extolling the brand's virtues to other addicts.

On the street, for both pushers and fellow addicts, an experienced addict's endorsement is considered as good as gold. Those who proclaim a drug's power, called "touters" in street jargon, routinely become walking advertisements for pushers. They are often used in the early morning hours when addicts gather to wait for heroin dealers.

"When I come out of my door in the morning, I see all these dealers on the corner," said the addict, a mother of three who asked to remain anonymous. "But I'm going to the one I know sells New Jack. I'm not going to anyone else, I'm going for the New Jack.

"When I get high, I love the high." said the addict, whose neck is scarred by broken pieces of hypodermic needles. "If I do it at 9 a.m., I won't have to go out on the street for some more until 2 p.m. or 3 p.m. If I do something else, I have to go out at 9:45 Before "New Jack Swing" appeared on the Baltimore heroin scene, the favored brand was another packaged heroin called "Bobby Brown." Named after the popular R&B; singer, that brand of heroin was about as pure as "New Jack Swing" but didn't have the extra kick of morphine.

"Bobby Brown" was cut with quinine or a baby laxative called mannite. It reportedly gave heroin addicts a high that could last eight to 12 hours. But after a female addict overdosed, local drug dealers took it off the market and replaced it with a less potent brand of heroin.

"It made them scared," said the addict, who began her habit seven years ago. "They were trying to find out who sold it to the girl, because if police could trace it back to the dealer who sold it to her, he could have been charged with murder."

Within weeks of "Bobby Brown's" demise, "New Jack Swing" hit the traditional heroin markets in West and East Baltimore and quickly won the favor of thousands of addicts. "New Jack Swing" and its potent rivals have become so prevalent in the Eastern District that the average purity of heroin seized there this year is 4.9 percent. Drug enforcement officers said this indicates that "New Jack Swing" has largely eliminated the cutting process by which some drug organizations diluted their heroin for street sale.

Capt. Michael Andrews, who heads the city police drug enforcement units, said the average street purity of heroin seized in Baltimore has increased in the past six years from about 3 percent to 5.3 percent. But the actual purity of heroin injected by addicts is about 2.5 percent.

Captain Andrews also said the increased purity of heroin seized on city streets means either that there is more heroin on the street or that various drug organizations are increasing the purity to take a greater share of the local market.