Trichomonas vaginalis was investigated by cervicovaginal cytology in pregnant and non-pregnant women receiving care at two public referral hospitals in Goiacircnia, Goias, Brazil. The frequency of Trichomonas vaginalis infection, the correlation between its presence and a diagnosis of precancerous and indeterminate lesions, and potential inflammatory changes in the vaginal epithelial cells in the presence of the parasite were evaluated.Overall, 359 Papanicolaou smears from 157 pregnant women and 202 non-pregnant women were evaluated.nbsp The principal inflammatory changes associated with the presence of T. vaginalis were registered.A second examiner reevaluated the slides. T. vaginalis infection was found in 46% of the slides, withprecancerous lesionsbeing found in 4.2% of the infected women.nbsp Perinuclear halos were the most common inflammatory change associated with the presence of the parasite.nbsp Adherence of the parasite to the vaginal epithelial cellsand ill-defined cytoplasmic borders were more commonly found in the group of pregnant patients.nbsp The prevalence of T. vaginalis was high in the present study, both in the pregnant and non-pregnant women.nbsp The socioeconomic level of the study population and the examinersrsquo experience played a particularly relevant role in the results obtained