Taking two drinks a day -- or a few glasses of wine -- may cut a man's chance of fatal heart attack to no more than one-third of either a non-drinker's or heavy drinker's.

A Harvard Medical School team reported this finding in the Journal of the American Medical Association yesterday. They thus confirmed, and in effect virtually certified, some similar results elsewhere that many doctors had been inclined to look on as tentative.

The Harvard doctors found that drinking "small to moderate amounts of alcohol had, "a protective effect" against fatal coronary disease in a group of 568 married men aged 30 to 70.

They also established for the first time that one could get this effect by drinking liquor, cocktails, beer, or wine, so long as daily intake was "less than or equal to" no more than two ounces of pure alcohol.

Two ounces of pure alcohol is about 4 1/2 ounces (a couple of fairly liberal shots) of 86 or 90 proof whiskey, or three and a third 12-ounce bottles of beer, or three four-ounce glasses of wine.

Dr. Charles Hennekens, head of the Harvard group, warned that "we're not telling people who don't drink to start drinking -- we're in no position to do that," because there is probably still much about moderate drinking that medicine doesn't know."

"What we can clearly say," he added, "is that heavy drinkers should cut down," partly because of what this study shows "but even more because of all other data on heavy drinking.