Women pay nearly 40 percent of the $50 million-plus in dues federal and postal unions collect each year. Yet they remain in the minority when it comes to the executive ranks of the organizations that represent them.

Federal and postal unions, who speak for more than half the government's workforce, are constantly pressuring Uncle Sam to clean up his act as an employer. They demand improved pay, grades and training opportunities in government for women. But some of the unions, probably a majority of them. would flunk the same "fairness test" if the government applied it to them.

Most of the top-paying jobs in federal unions are held by elected officers. Among the national level of the white-colar federal unions, the officer corps is still largely a male preserve.

More women are running for, and winning, top local union jobs. And many unions now have women as regional recruiters and local contract negotiators and representatives. Some are political appointees for window-dressing purposes. But the majority get and keep the jobs because they do them well.

Neither the government nor the unions have good data on the number of women in the latter's membrship ranks, but unions themselves estimate that from 30 percent of 55 percent of their members are women.

Despite their numbers and the high percentage of money they contribute to support the unions, women remain underrepresented in most elected, appointed and top staff jobs. There are some notable exceptions:

Joyce Turney, president o f the influential National Association of Postmasters. She came up through the ranks of the postal service (postmaster of South pasadena, Calif.) and NAPUS, which is the major management-level organization of the mail corporation.

Anne Sullivan, legislative director of the National Association of Government Employes. She's a former House Ways and Means Committe staff member and now serves as chief lobbyist for the independent union.

Rita Hartz, national secretary-treasurer of the National Federation of Federal Employes since 1970 and one of the top-ranking women in the government labor movement. NFFE, often considered one of the more conservative unions, has a number of women in top posts, including Janet Cooper, associate general counsel; Robbie Exley, head of the Defense Department support unit; Linda Spell, field news editor; Tina Gray, head of the insurance division, and Nancy McWilliams, director of field coordination, now on maternity leave.

At the American Federation of Government Employes, Louise Smothers heads the women's affairs department; Jeannette Abrams is managing editor of the Washington Newsletter, and Peggy Kans is administrative assistant to Nick Nolan, AFGE's secretary-treasurer.

Two of the 14 executive board members of the National Treasury Employes Union are women: Blondell Ganey is administrative controller (the third ranking job in the union), and Laura Negin is assistant editor of the newspaper that goes to 70,000 members.

A top federal official who watches the government labor movement said neither the government nor its unions have "particularly good records regarding women in top jobs."

He feels that labor unions are "several years behind" the federal government in moving qualified women into leadership positions.

Once the women realize their clout and their dollars and cents value to unions, there ought to be a lot more of them at executive board meetings who do things besides taking notes and fetching coffee.