Stephen A. Nye, 42, a lawyer and a member of the Federal Trade Commission from 1974 to 1976, died Wednesday night at George Washington University Hospital of a liver ailment.

A seasoned litigator before his appointment to the FTC, Mr. Nye believed that efforts to enforce the anitrust and consumer protection laws should combine creativity with a sense of the practical. As a member of the FTC, he took a special interest in strengthening and streamlining the commission's investigative and adjudicative procedures.

A sense of humor not generally associated with regulatory agencies also permeated his tenure at the FTC. Soon after he came to the agency, its public comment section began to get handwritten letters from a witty Wm. F. (Fred) Bunch, a "concerned citizen" who urged the agency to protect consumers - "us little people" - but only in a manner that would really benefit them. Commission staff eventually learned that Bunch was Mr. Nye's nom de plume.

Occasionally the letters told the FTC to stay out of an area that was "none of its buiness" and to spend its money on more important projects. Sometimes the FTC was lambasted for not acting in a stronger manner. The letters always reflected the writer's (Mr. Nye's) view that what government does, it ought to do well.

After resigning from the commission, Mr. Nye became a partner in the Washington law firm of Howrey and Simon, where he resumed private anitrust ligitation work. He withdrew from the firm last year.

Mr. Nye was born and reared near Phoenix, Ore. He graduated from Stanford University with honors in 1957, served as an Army intelligence officer until 1959, and then entered Harvard Law School. After receiving his juris doctor degree in 1962, he joined the San Francisco law firm of Pillsbury, Madison and Sutro.

He left the firm in 1968 to serve as general counsel to the Competitive Capital Fund. In 1970, he became a partner in the San Francisco firm of Sullivan, Jones and Archer and was an antitrust litigator there until his appointment to the FTC.

He is survived by his wife, Mary Ruth, and a daughter, Crichton, both of the home in Washington; three other children, Dierdre, Stephen and Anna, of White Water, Wis., and his parents, Mr. and Mrs. Stephen Nye, of Medford, Ore.

The family suggests that expressions of sympathy be in the form of contributions to St. Francis Burial and Counseling Society in Washington. CAPTION: Picture, STEPHEN A. NYE