The vastly outnumbered female members of Congress have been complaining for years about unequal treatment by their male colleagues, but they have at least one perquisite the men don't: a suite in the Capitol for their exclusive enjoyment.

The hideaway suite, unmarked save for the room number, 235, was set aside in 1961 as the Congresswomen's Lounge and has been one of the Capitol's best-kept non-secrets. The ornately furnished suite includes a large, high-ceilinged main room with an elegant crystal chandelier, a fully equipped kitchen, lavatory facilities and a small area where the lounge attendant has her desk, takes messages for the congresswomen and schedules luncheons, receptions and conferences in the suite.

In fact, it was an incident involving the position of lounge attendant that has threatened to disrupt the discreet operation of the Congresswomen's Lounge with the kind of publicity usually associated with the smoke-filled rooms where male members of Congress hang out. It seems that Rep. Patricia Schroeder (D-Colo.), who oversees Suite 235 as head of the Congresswomen's Caucus, is just one of the boys where patronage is concerned.

Kathleen Hill had been the suite manager, and she told our reporter Gary Clouser that her grandson-in-law, Rep. Bob Carr (D-Mich.), had gotten her the job. The week that Carr's divorce became final, Hill was fired. Carr declined comment, but Hill said she suspects that he asked his friend Schroeder to fire her.

Ann Thornburgh, administrative assistant in the House doorkeeper's office, was the one who told Hill her services were no longer required. Thornburgh told us Hill is a "lovely lady" and had done a fine job running the Congresswomen's Lounge.

Thornburgh acknowledged that Hill's replacement, Ann Murphy, was hired at Schroeder's recommendation. Murphy's husband, Richard, was congressional liaison for the ill-starred presidential campaign of Gary Hart, former Democratic senator from Colorado and a close associate of Schroeder. Schroeder is considering a race for the presidential nomination herself.

Dan Buck, a Schroeder administrative assistant, acknowledged that the lounge attendant's job is a patronage appointment and that Schroeder "has a role in filling the position." But he pointed out that losing a patronage job is not a reflection on the employe's performance or competence.

Buck said that Schroeder, who used to complain publicly and often about the second-class treatment of female members of Congress, now believes congresswomen have made significant strides toward equality in access to Capitol Hill facilities.

The Senate, which has only two women, has no separate facilities for them. Female House members, who currently number 23, have a separate gymnasium from their 412 male colleagues. The House swimming pool is segregated, with separate hours scheduled for men and women.