To evaluate the presence of infectious agents for vaginitis in patients with ASCUS. 33,388 patients who underwent cervical-vaginal cytology from 08/1993 to 05/2002 were included in the study, and 1,104 (3.4%) presented positive ASCUS. The appraised infectious agents were Coccobacilli, Candida sp, Trichomonas vaginalis, and clue cells (Gardnerella vaginalis). In the group with ASCUS a larger frequency of Coccobacilli (22.37%) and Trichomonas vaginalis (5.25%) was found when compared with the group with negative ASCUS (17.79% and 3.98%, respectively; p < 0.05). Cytolysis occurred more frequently in patients with ASCUS (3.8 vs 6.3%, first phase and 4.5 vs 10%, second phase). We believe that some diagnoses of ASCUS can be induced by the presence of infectious agents for vaginitis, mainly cocci and coccoides. ASCUS occurs more frequently in the first phase of the menstrual cycle, therefore in less acid vaginal pH.