A prospective study was performed involving 101 women who consecutively attended a primary health care unit for complaints of genital malodour and/or abnormal vaginal discharge. Bacterial vaginosis was diagnosed in 34 women on the basis of four diagnostic criteria: vaginal pH greater than 4.7, homogeneous vaginal discharge, a positive amine test and clue cells. The sensitivity of these criteria was greater than 90% except for homogeneous discharge (82%). Their specificity was greater than 90% except for vaginal pH greater than 4.7 (46%); a specificity of 87% could have been achieved by using the criterion for vaginal pH greater than or equal to 5.0. There was a strong association between diagnosis of bacterial vaginosis and the concomitant occurrence of Gardnerella vaginalis, Mobiluncus spp. and Bacteroides spp. There was no difference between women with or without bacterial vaginosis as regards contraception methods (except for use of an intrauterine device), age at first intercourse, or earlier episodes of vaginal discharge. Sexual transmission of the predominant bacteria was not supported by data collected from the male consorts.