There has been a global increase in cesarean section rates. While this has improved perinatal outcome, it is associated with complications such as wound infection. We determined risk factors for cesarean section wound infection in a tertiary hospital in Lagos, Nigeria. We prospectively studied a cohort of 906 women who had cesarean section at the Obstetrics Unit of the Lagos State University Teaching Hospital between January 1, 2011, and December 31, 2011. A comparison was made between 176 women who had wound infection and 730 women who did not using logistic regression. Of the 2134 deliveries during the study, 906 (42.5%) had cesarean section and of which 176 (19.4%) had wound infection. Independent risk factors for wound infection were: preoperative anemia (adjusted odds ratio [aOR]= 1.88; 95% confidence intervals [CI]= 1.03–3.41; P= 0.0396), presence of diabetes mellitus (aOR= 7.94; 95% CI= 1.60–39.27; P= 0.0111), HIV infection (aOR= 6.34; 95% CI= 1.74–23.06; P= 0.0051), prolonged operation time (aOR= 2.30; 95% CI= 1.19–4.42; P= 0.0127), excessive blood loss at surgery (aOR= 5.05; 95% CI= 2.18–11.66; P= 0.0002), and chorioamnionitis (aOR= 9.00; 95% CI= 1.37–59.32; P= 0.0224). Patients with HIV infection, diabetes mellitus, preoperative anemia and chorioamnionitis have an increased risk of postcesarean wound infection as is when surgical time exceeds 1 h or when associated with blood loss> 1l.