A prospective study to evaluate the prevalence of specific microorganisms in pregnant and nonpregnant women with cervicovaginitis attended at the Instituto Nacional de Perinatología, was done; Candida sp, Gardnerella vaginalis, Replasma urealitycum, Chlamydia trachomatis, Group B Streptococcus, Trichomonas vaginalis, Neisseria gonorrhoeae were investigated. Two hundred thirty four patients were studied, 105/234 (44.9%) pregnant and 129/234 (55.1%) nonpregnant women, with a mean age of 26.5 years (range 14 to 44 years). One hundred eighty one (77.5%) women had only one sexual partner. The most common microorganisms seen were Candida sp (31.6%), Gardnerella vaginalis (27.7) and Ureaplasma urealyticum (15.8%). Infection by Chlamydia trachomatis was documented in 9.8% of the population. Trichomonas vaginalis was identified in 1.7%, there was not any case of Neisseria gonorrhoeae infection. Candida sp and Ureaplasma urealyticum were founded more frequent in the pregnant women than nonpregnant women, 41.9% vs. 24.8% (p less than 0.01) and 20% vs. 12.4% (p less than 0.05) respectively. Group B Streptococci was isolated as a single agent in 4.8% in pregnant women. There were not found any pathogenic microorganisms in 29.9% of the cases, as a causal agent of symptomatic cervicovaginitis.