The prevalence of 3 mycoplasmas (Mycoplasma hominis, Ureaplasma urealyticum and Mycoplasma genitalium) was determined in a cohort of women with or without bacterial vaginosis (BV) and in their respective male partners. Heterosexual women with or without BV and their male partners were recruited and genital sampling for these microorganisms was performed. Seventeen women with BV and 21 women with normal flora, and their respective male partners, were recruited. M. hominis was present in 9 (53%) of 17 women with BV compared with none of 21 women without BV (P=0.0001). Of the 17 male partners of women with BV, 8 (47%) had M. hominis compared to 5 (24%) of 21 male partners of women without BV (not significant [n/s]). U. urealyticum was detected in 11 (65%) of 17 women with BV in comparison with 10 (48%) of 21 women without BV (n/s). U. urealyticum was present in 4 (24%) of 17 male partners of women with BV compared to 6 (29%) of 21 male partners of women without BV (n/s). M. genitalium was not detected in any of 15 women with BV and in only 2 (12%) of 17 women without BV (n/s). M. genitalium was present in 4 (25%) male partners of 16 women with BV in comparison with 3 (16%) male partners of 19 women without BV (n/s). Thus, M. hominis was the only mycoplasma detected significantly more often in women with, rather than in those without, BV. None of the mycoplasmas was found significantly more often in male partners of women with, rather than those without, BV. Overall, M. genitalium behaved somewhat similar to Chlamydia trachomatis. It was the least commonly occurring mycoplasma, a reflection perhaps of the relatively low incidence of partner change in this study population.