OBJECTIVE: To estimate the incidence of and define risk factors for postpartum infectious complications after vaginal birth after cesarean (VBAC) complicated by chorioamnionitis. STUDY DESIGN: A secondary analysis of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal-Fetal Medicine Unit Cesarean Registry was performed. The primary outcome was a composite of postpartum infection: endometritis, sepsis, pelvic abscess, urinary tract infection, necrotizing fasciitis, and septic pelvic thrombophlebitis. Peripartum predictors were compared using parametric and nonparametric tests, as appropriate, and multivariate predictors assessed using logistic regression. RESULTS: A total of 559 subjects had chorioamnionitis in labor and a successful VBAC. Twenty-four (4.3%) subjects experienced the primary outcome, mainly due to endometritis (19/24). Significant factors included preterm delivery <32 weeks (odds ratio [OR]: 3.05, 95% confidence interval [CI]: 1.32-7.06) and body mass index (BMI) ≥40 (OR: 4.63, 95% CI: 1.25-17.14). Receipt of postpartum antibiotics was protective against postpartum infection (OR: 0.28, 95% CI: 0.12-0.65). In multivariate analysis, preterm delivery <32 weeks, BMI ≥40, and receipt of postpartum antibiotics remained associated with postpartum infection. CONCLUSION: Nearly 5% of women with chorioamnionitis had a postpartum infectious complication after vaginal delivery, with higher rates in those delivering at <32 weeks and with prepregnancy BMI ≥40. Receipt of postpartum antibiotics decreased the odds of postpartum infection markedly.