WASHINGTON (AP) _ The Supreme Court ruled today that a federal appeals court mistakenly overturned the 1988 racketeering convictions of reputed former mob boss Anthony ''Fat Tony'' Salerno and seven other men.

The 8-1 decision ordered further lower court hearings that could lead to reinstatement of the convictions.

The ruling gives prosecutors more leeway in excluding from criminal trials evidence that could favor defendants.

Justice Clarence Thomas, writing for the court, said the 2nd U.S. Circuit Court of Appeals misinterpreted federal rules of evidence when it overturned the convictions of Salerno, reputed ex-boss of the Genovese crime family in New York, and the others.

The men were convicted, after a 13-month trial, on charges that included loansharking, bid-rigging, union fraud, extortion, gambling and a murder conspiracy.

Much of the prosecution focused on the Genovese Mafia gang's alleged infiltration of the New York City concrete industry.

Prosecutors said that between 1980 and 1985 the Genovese crime family tried to rig bids for concrete superstructure work on virtually every high-rise building in Manhattan that used more than $2 million worth of concrete.

The Genovese family created a ''club'' of six concrete companies that supplied the crime family with kickbacks in return for securing construction contracts, prosecutors said.

Salerno, 80, was sentenced to 70 years in prison for his role in the alleged racketeering scheme. He already was serving a 100-year federal sentence for another racketeering conviction.

The others whose convictions were overturned are:

-Matthew ''Matty the Horse'' Ianniello, a reputed Genovese family member who had been sentenced to 13 years in prison.

-Edward ''Biff'' Halloran, a concrete supplier sentenced to 13 years and ordered to give up his interest in the Certified Concrete Co.

-Nicholas Auletta, a Westchester County businessman sentenced to 11 years and ordered to forfeit his interest in S&A Concrete.

-Vincent DiNapoli, sentenced to 24 years and fined $266,000.

-Louis DiNapoli, sentenced to 14 years and fined $266,000.

-Aniello Migliore, sentenced to 24 years and fined $266,000.

-Alvin Chattin, sentenced to six years and fined $16,000.

Prosecutors told the defendants before their trial that Pasquale Bruno and Frederick DeMatteis, owners of the Cedar Park Concrete Construction Corp., had testified under immunity before a grand jury and might be sources of exculpatory testimony.

Prosecutors alleged that Cedar Park Concrete was one of six companies in the Genovese family's club, but Bruno and DeMatteis denied participation in, or awareness of, any such scheme.

The defendants' lawyers subpoenaed Bruno and DeMatteis as trial witnesses. But both men refused to testify, invoking their Fifth Amendment privilege against self-incrimination. Prosecutors refused to give the two men immunity at the trial.

The defendants' lawyers sought to have the grand jury testimony of Bruno and DeMatteis admitted as evidence. But U.S. District Judge Mary Johnson Lowe refused.

The 2nd Circuit court said the evidence should not have been excluded and overturned the convictions.

The case is U.S. vs. Salerno, 91-872.