A federal judge yesterday dismissed a suit against The Washington Post by 99 of its employees, ruling that reporters and editors in a representative sample are professionals under federal labor law and not entitled to overtime pay.

U.S. District Judge Gerhard A. Gesell said in his opinion that the newspaper employees had misconstrued the 53-year-old Fair Labor Standards Act and that the reporters and editors are exempt from the general requirement of the law that employers pay time-and-a-half to employees who work more than 40 hours in a week. The law exempts executive, administrative and professional employees.

The judge said that the 13 newsroom employees in the sample group selected by both sides were all exempt from the overtime provision of the law because they met the definition of professional employees.

"They produce original and creative writing of high quality within the meaning of the regulations," Gesell said. "They have far more than general intelligence . . . their performance as writers is individual, interpretative and analytical both in writing itself and in the process by which the writing must be prepared; and their status is measured and paid accordingly."

Gesell's opinion did not mention commercial department employees or newsroom aides who also were seeking overtime compensation.

The suit against The Post is one of two such cases that are being watched closely by the newspaper industry because of their financial importance and the potential impact on newsroom management.

Gesell said the Post employees had pursued the suit in an improper attempt to influence collective bargaining negotiations with the newspaper. Although some employees might be underpaid, Gesell said, "this matter remains to be resolved at the bargaining table."

The Post and the Washington-Baltimore Local 35 of the Newspaper Guild have been unable to reach an agreement since the newsroom contract expired in July 1986.

In August, Post management declared talks at an impasse and instituted its last wage offer.

Although the newspaper had asked for a blanket exemption for its employees, Gesell left open the possibility that some of the 99 employees might be entitled to overtime. The judge dismissed 13 of the cases with prejudice based on depositions filed by the employees, effectively ending the chance of the cases going to trial unless the decision is overturned on an appeal.

He also tossed out the remaining 86 cases, but said those employees could file new suits individually.

Gesell's across-the-board dismissal was in stark contrast to his remarks at a hearing in the case last month, when he said the various claims might require 99 separate trials.

Robert Paul, an attorney for the employees, said Gesell's opinion was "bizarre" because it dismissed all of the employees' claims while factual disputes were still unresolved.

Paul also said Gesell's decision "flies in the face of established law."

Post reporter Tom Sherwood, the lead plaintiff in the case and chairman of the newspaper's Guild local, said the decision "slows our momentum."

Post Executive Editor Benjamin C. Bradlee said: "Of course we are pleased. We treat journalists as professionals at this newspaper."

John Kester, an attorney for The Post, said, "This is an important decision, and everyone in the field of journalism should be pleased by the decision." Kester declined to comment on the ruling's precise impact on The Post, saying he was still studying Gesell's opinion.

At The Post, the issue of overtime compensation has been a sticking point in each contract negotiation in recent years. For many years, employees receiving less than a specified salary -- currently $810 a week under contract terms instituted by The Post in August -- are entitled to overtime compensation for each hour worked in excess of 37.5 hours a week.

Employees receiving more than $810 a week are entitled to compensatory time off for most overtime worked, said Managing Editor Leonard Downie Jr.

Gesell noted in his opinion that most of the plaintiffs earn more than $810 a week. According to figures compiled by the Guild, the average salary for Post reporters is $1,071 a week, or $55,692 a year.