BOSTON (AP) _ Twenty years ago, Bobby Fischer was a hero and the game he dominated became a craze. Department stores sold out their chess sets.

Now, chess enthusiasts say Fischer's rematch with Boris Spassky may be launching a second ''Fischer boom.''

''We're getting phone calls around the clock,'' said Daniel Edelman, assistant director of the U.S. Chess Federation. ''It's taking off like crazy.''

The game has a lot of catching up to do. Many say Fischer, the only American world chess champion, took chess with him when he went into seclusion in the mid-1970s.

''The publicity that Fischer created left as he left the field,'' said Dr. Michael Charney, head of the Chess-Games Project, a chess program for kids in Boston's inner-city. The fascination with Fischer and his championship victory over Spassky in Iceland was fed partly by the symbolism of a contest between an American and a Russian at the height of U.S.-Soviet tensions.

''(Fischer) was representing the United States in the Cold War,'' Charney said.

But Americans also recognized a genius at work. Fischer's skill had them watching his matches on television, reading chess moves in the newspapers and buying out store supplies of chess boards.

''He reached the mainstream culture in the United States and he was probably the first to do so in a hundred years,'' said Leon Haft, president of the Marshall Chess Club in New York City.

Membership in the New Windsor, N.Y.-based national chess federation zoomed from 20,000 to a high of 59,000 in the early 1970s, Edelman said.

In 1975, Fischer was stripped of his title by the International Chess Federation for refusing to defend it against Anatoly Karpov. Fischer would not acknowledge the decision and dropped out of chess competition.

With chess' American hero gone, U.S. interest faded.

The problem is that there's no visual thrill in a board game that can last hours, said Roy Schotland, chairman of the U.S. Chess Center in Washington.

''It doesn't have the obvious dramatic action of a hockey game,'' Schotland said. ''Even a hockey game isn't exciting enough so you have to have brawls.''

One spectator at the U.S. women's chess championships last month in Waltham, Mass., said it was '''like watching paint dry,''' said Joel Altman, coordinator of the event.

Despite the falloff in interest after Fischer dropped out of sight, chess has been making strides in the past few years, especially among young people.

The U.S. Chess Federation now has 65,000 members, less than 10 percent of them women.

Organizers in cities including Boston, Philadelphia and New York City are running chess programs for inner-city youths.

About 1,200 children played in the national elementary school championships held in Knoxville, Tenn., in April, Edelman said. Ten years ago, the competition would have drawn 200 at most, he said.

''If you can visualize 1,000 elementary school students sitting quietly in a large gymnasium or arena, it's a sight to behold,'' Edelman said.

More American interest is expected when reigning world chess champion Garry Kasparov defends his title in Los Angeles in the fall of 1993. His challenger has not yet been determined.

''We're probably at the state where tennis was several decades ago,'' Edelman said. ''Chess is just opening up and it's ripe for investment by companies.''