Background In sub-Saharan Africa, there are limited data on the incidence of sexually transmitted infections (STIs) among women, largely because routine screening for asymptomatic infection is not performed. We conducted a secondary analysis to measure STI incidence rates and determine risk factors for new STI acquisition among women enrolled in the VOICE trial. Methods We analyzed data from 4843 women screened for chlamydia, gonorrhoea, syphilis, and trichomonas infection at baseline, annually, at interim visits when clinically indicated and at their study termination visit. Risk reduction counseling and condoms were provided throughout the trial. Results Twenty percent of evaluable participants had one or more curable STIs at baseline. Over 5660 person-years at risk (PYAR) of observation, incidence rates were 13.8% (95% confidence interval [CI], 12.7-14.8) PYAR for chlamydia, 3.5% (95% CI, 3.0-4.1) PYAR gonorrhea, 0.1% (95% CI, 0.6-1.1) PYAR syphilis, and 6.6% (95% CI, 5.8-7.2) PYAR trichomoniasis. South African sites had the highest incidence of chlamydia. The Uganda site had the highest incidence of gonorrhoea and syphilis, and Zimbabwe the lowest incidence overall. The majority of these cases were diagnosed at a routine scheduled testing visit. In multivariate analysis, positive baseline STI, younger than 25 years, being unmarried, and some alcohol consumption were associated with acquiring a new STI. Conclusions We observed high rates of STIs during follow up among women in the VOICE study. Women living in human immunodeficiency virus endemic countries should be screened for common STIs.