Vaginal washings from women attending a veneral disease clinic were examined for the presence of protease that cleaved IgA subclass 1 (IgA1). In a crude assay, vaginal washings cleaved [125I]IgA1 in 19 of 25 specimens from individuals from whom Neisseria gonorrhoeae were cultivated. Forty-six specimens from 104 women whose cultures were negative for N. gonorrhoeae also cleaved [125I]IgA1. Vaginal washings from six of six women with culture-proven gonorrhea cleaved [125I]IgA1 into low-molecular-weight components identical to those produced by partially purified IgA1-specific protease from gonococci. The hydrolysis of [125I]IgA1 by vaginal washings from women whose cultures were negative for N. gonorrhoeae yielded cleavage products that resembled those of trypsin or alpha-chymotrypsin. These findings indicate that gonococci residing in the female genital tract produce IgA1-specific protease that can be detected in the vaginal washings of infected women.