The House ethics committee's investigation into Rep. Barney Frank's relationship with prostitute Stephen L. Gobie dismissed as unfounded the most serious allegations against the Massachusetts Democrat, but said he violated House rules by fixing 33 parking tickets and writing a memorandum that "could be perceived as an attempt to use political influence" on Gobie's behalf.

In releasing the 57-page report yesterday, chairman Julian C. Dixon (D-Calif.) said the Standards of Official Conduct Committee had determined the two issues were serious enough to constitute a violation of a catchall House rule requiring lawmakers to conduct themselves "at all times in a manner which shall reflect creditably on the House of Representatives." Frank's actions, the report said, brought "discredit" on the House.

Frank, at a news conference in his Massachusetts district, said, "I accept the judgment of the committee report. . . . I accept this conclusion that I showed poor judgment."

The committee's unanimous decision on Thursday to recommend that the House formally reprimand Frank sets in motion a disciplinary process that is expected to provoke a political battle on the House floor next week. Rep. William E. Dannemeyer (R-Calif.) has said he will ask the House to expel Frank. If that fails, it is likely there will be an attempt to censure him.

However, both Democrats and Republicans said yesterday that the full House is likely to support the committee's recommendation of a reprimand, a less severe discipline than censure that also requires a vote in the House.

The ethics committee report, the product of a 10-month probe by the 12-member group, rejected several accusations made by Gobie, including charges that Frank sanctioned use of his apartment for prostitution, that he pressured probation officers not to extend Gobie's probation on sex and drug convictions and that he engaged in sexual acts with Gobie in the House gymnasium.

Gobie's veracity was vigorously challenged on numerous issues throughout the report, which is also highly critical of some news accounts that were based on interviews with Gobie. Frank, using his funds, employed Gobie as a personal aide for a two-year period beginning in 1985.

"In summary, the testimony provided by Mr. Gobie has, in many cases, been contradicted or refuted by other testimony or documentary evidence," the report concluded.

Though the ethics committee's report is exhaustive on some questions surrounding Frank's relationship with Gobie, it left unanswered one question. The panel deleted the name of the person to whom Frank wrote a memo on Gobie's behalf that the committee charge contained misleading information and which eventually found its way to Virginia Commonwealth Attorney John Kloch.

A spokesman for the committee said the deletion was a judgment call by the panel and that the investigation found no reason to dispute Frank's assertion that the memo was not directed at "any decision-maker." The report did not explain how the memo came into the possession of Kloch, who testified that the document had no effect on his decision to extend Gobie's probation.

Frank declined to name the individual to whom the memo was addressed, saying "I won't get anybody else involved in this."

The memo contained two misleading statements by Frank that "were directly relevant to any consideration of whether Mr. Gobie's probation should have been extended," the committee ruled. In the memo, Frank stated that he had met Gobie through mutual friends, when in fact he met him through a newspaper advertisement for an escort service. He also said Gobie was adhering to the requirements of his probation when Frank knew that Gobie was engaging in prostitution at the time.

In addition to the memo issue, the panel found that in 33 instances, Frank had fixed parking tickets received by himself and Gobie that were not related to official congressional business. The committee directed Frank to reimburse the D.C. government.

Though Dixon said the violations by Frank were "serious," he also implicitly acknowledged that the outcome may have been affected by the issue of Frank's homosexuality. Several other sources involved in the probe, who asked not to be identified, said the politically sensitive question of Frank's gay lifestyle had a major impact on the decision to recommend a reprimand.

"The entire color surrounding the circumstances certainly was discussed," said Dixon at a Capitol Hill news conference yesterday.

Two other members of the House charged with sex-related transgressions recently received more lenient treatment than Frank. Rep. Jim Bates (D-Calif.) was admonished by letter for sexually harassing female aides, and Rep. Gus Savage (D-Ill.) escaped a similar admonishment by apologizing to a Peace Corps volunteer in Zaire who accused him of making aggressive sexual advances that she considered an assault.

Sources familiar with the Frank inquiry said the committee, which is composed of six Democrats and six Republicans, was split 7 to 5 in favor of recommending a less severe punishment in the form of a letter to Frank admonishing him for his conduct. But the sources said Frank agreed to accept a reprimand even as his Democratic supporters on the panel were concluding that a reprimand recommendation might avert a bloody and costly partisan battle in which their party would be portrayed as pro-homosexual.

Many Democrats also believed that a divided verdict by the committee would likely be overturned on the House floor in favor of a reprimand if Republicans turned it into a major political issue so close to the November congressional elections.

Frank, a witty and acerbic liberal who enjoys wide popularity in his district and in the House, appears well positioned to prevail in his reelection campaign. His only GOP opponent, accountant John Soto, is a political unknown.

"Clearly, there are people in the district who are as upset with him as he was with himself, on a personal level," said state Rep. Susan Schur, a Newton Democrat. "But that's not what they are voting on." Schur said Frank's constituents have had enough time to digest the issues surrounding the investigation and that the reprimand is "irrelevant and the impact is nil."

"The jury is out on how this will impact Barney near-term," said Rep. Dennis E. Eckart (D-Ohio). "But he's been open and apologized and that's important."

Rep. Robert K. Dornan, a conservative California Republican, predicted a "big bloody fight" on the floor that would not be quickly forgotten. It is likely, Dornan said, that Republicans will ask at the beginning of every Congress that Frank be stripped of any subcommittee or committee chairmanships he holds.

While acknowledging that a reprimand "is not a nomination for a Nobel prize," Frank yesterday predicted that his stature and effectiveness in the House would not suffer any long-term effects.

Staff writer John E. Yang and special correspondent Christopher B. Daly contributed to this report.