Bisphenol-A (BPA) is an endocrine disruptor with widespread human exposure. The effect of in utero BPA exposure on human offspring remains largely unknown. METHODS: Anogenital distance (AGD) of sons of workers who did or did not have occupational BPA exposure during pregnancy were compared in an occupational cohort study. Parental BPA exposure level during the index pregnancy was estimated through a job-exposure matrix based on personal air sampling measurement. Maternal exposure was considered direct in utero exposure to the fetus, whereas paternal exposure was considered indirect in utero exposure. RESULTS: A total of 153 boys were included in the final analysis, among them 56 with parental occupational exposure during pregnancy and 97 without. After controlling for the boys' ages and weights using linear regression, parental occupational exposure to BPA during pregnancy was associated with shortened AGD in male offspring. The association was stronger for maternal exposure (p < 0.01). There was also a dose-response relationship with increased BPA exposure levels in pregnancy associated with greater magnitude of shortened AGD in male offspring, with a statistically significant trend for the association (p 5 0.008). CONCLUSION: Our findings provide the first epidemiologic evidence that in utero BPA exposure may adversely affect male genital development. Birth Defects Research (Part A) 91:867-872, 2011. ร 2011 Wiley-Liss, Inc.