All last week mibsters from 11 states and the District of Columbia shot it out at this seaside resort. Washingtonians battled Virginians. Virginians took aim against Marylanders, Marylanders tried to knock off Washingtonians.

Gangland slayings in the boardwalk? War between the states?

Nothing of that sort. It was the 55th Annual National Marbles Tournament, sponsored by the "Big Blue Marble" TV show, which attracted 54 mibsters - the marble shooters term for themselves.

After four days of heated competition, the boy and girl national champs, both 13-year-old Pennsylvanians, were crowned by the mayor of Wildwood dean Fenauer, of Reading, and Diane Bertosh of Pittsburgh, each received a $500 college scholarship from IT&T.

Although the metropolitan Washington area was well represented, the shooters didn't fare very well. None of them made it into the final rounds of competition though they all said that they were enjoying their week in Wildwood.

This is the first year that Hyattsville has had marbles competitions. Sean Ganey, 12, of 4122 40th Place the red-headed, Hyattsville boys' champ said that the competition at the nationals was tougher than in Maryland. "They're better shooters here," he said. "How much better?" "A lot."

Kevin Zeigler, a staff leader with the Hyattsville recreation department, said that both Ganey and the Hyattsville girls' champ, Shirley Hoffman, 12, 3817 Hamilton St., have only been shooting for two months. They will be eligible for national competition for the next two years, he said and that will give tham a chance to improve.

"I heard the boy from Reading, Pa., practiced six hours a day for the past few months," said Zeigler. The Hyattsville kids were "not used to the exposure. I think they're doing quite well considering some of the other kids have been playing for a few years."

This is also Takoma Park's first year in the nationals. The city was represented by the brother-sister team of John, 10, and Carol Fotopoulos, 12, of 7700 Blair Rd, both of whom have been shooting for two years.

Four youngsters represented Cumberland, Md.: Beth Blankenship, 10; Jeff Kimmell, 10; Vance Ridgeley, 10 and Sharon Spitzer, 14. Darryl Fletcher, 12, represented Baltimore and Chris Carter, 11, represented Casanova, Va.

What the metropolitan youngsters lacked in success, they made up in spunk. Washington's Steve Morgan and Henry Frazer, 10, 240 W St. NW., rushed over to the judge's table after the announcement that the voting for "the best sport on the beach" was taking place. "Can you vote for yourself?" they asked almost in unison.

Roger Howdyshell, the president of Marble King Inc., one of five marble manufacturers in the country, has attened the tournaments since 1968. "When I was a kid the country was coming out of the Depression and were cheap," he said. "Give a kid a handful of marbles and he'd be busy for days . . . I'll tell you: It's still there," he said of the game's popularity. "I've never seen a kid who didn't like marbles."

During the last day of the preliminaries, Richard Kauffman, assistant to the director of the Alexandira recreation department, announced over the public address system: "Any boy champion who has not yet had his picture taken . . . " "No, any boy, not just the champions," interrupted "Big Blue Marble" public relations man Steve Schechter. Kauffman, his microphone turned off, turned to Schechter and said, "Well, it doesn't matter. They're all champions, Steve. They're all champions."

Oka Hester, the tournament director since 1937, was aksed whey he comes every year.

"I don't know. I never found out," Hester replied. "Psychiatrists tell you (June is) the time of the year you lose your mind."

Or your marbles.