Medical abortion regimens have become widely used, but the frequency of infection after medical abortion is not well documented. This systematic review provides data on infectious complications after medical abortion. We searched Medline for articles written before July 2003 to determine the frequency of infection after medical abortion up to 26 weeks of gestation. We reviewed all articles and extracted data on the frequency of infection from 65 studies. The frequency of diagnosed and/or treated infection after medical abortion was very low (0.92%, N = 46,421) and varied among regimens. Results of this review confirm that, with respect to infectious complications, medical abortion is a safe and effective option for first- and second-trimester pregnancy termination. After accounting for regional variations in diagnosis, there is little difference in frequency of infection among the regimens reviewed. Future studies should report clear diagnosis and treatment standards for infection so that more precise information becomes available.