Objective: To determine whether assisted conception increases the risk for mother-to-child transmission of hepatitis B virus (HBV) infection compared with natural conception. Design: Prospective cohort study. Setting: Research laboratory. Patient(s): A total of 305 children, 176 born with assisted conception and 129 born with natural conception, were born to a total of 251 hepatitis B surface antigen-(HBsAg-) positive women. Intervention(s): None. Main Outcome Measure(s): The seropositive rates of HBsAg in children at birth and HBV infection rates at 9-15 months of age. Result(s): Overall, 7.5% (23/305) of children were HBsAg-positive at birth. The rate of HBsAg-positive children at birth did not significantly differ between children in the assisted conception group compared with those in the natural conception group (6.3% [11/176] vs. 9.3% [12/129]). Multivariate logistic regression analysis showed that conception method is not related to the rate of HBsAg-positive children at birth. All children who were positive for HBsAg at birth and were followed up for 9-15 months became negative for HBsAg after hepatitis B immunization. Conclusion(s): Assisted conception does not increase the risk for mother-to-child transmission of HBV compared with natural conception. ((C) 2018 by American Society for Reproductive Medicine.) El resumen esta disponible en Espanol al final del articulo.