There is a close association between Trichomonas vaginalis (TV) infection and bacterial vaginosis (BV). Evidence indicates that the association is stronger with intermediate Nugent score than BV. The present study aimed to assess the association of TV infection with BV and with intermediate Nugent score. This was a cross-sectional hospital-based study involving 1110 non-pregnant women from Odisha state, India, aged between 18 and 45 years. Vaginal swabs were obtained for diagnosis of BV by Nugent score (NS) criteria and TV by PCR analysis. TV infection was found in 13.3% of women with intermediate Nugent score (NS 4-6) and 13.6% with BV (NS 7-10). Before adjustment, TV infection was shown to be associated with BV, intermediate Nugent, vaginal pH ≥ 4.5, and age group between 26 and 35 years. Multivariate analysis revealed that TV infection was more likely to have raised vaginal pH, either BV or intermediate Nugent. Proportion of TV cases was found to increase in a sequential manner with increase in Nugent score up to NS 6, after which a decline was noted. Vaginal pH was higher in the TV-infected group as compared to the uninfected group in women with intermediate Nugent score. However, there was no difference in women with BV. TV infection had an equal prevalence in women with intermediate Nugent score as well as BV. Therefore, in the intermediate Nugent score group, TV infection was found only in the setting of raised vaginal pH, thus pointing towards a pivotal role of vaginal pH in determining TV infection. The study is published online in Parasitology Research.