Studies demonstrate that many clinician populations have poor knowledge of and harbor negative attitudes towards intrauterine devices (IUDs). We set out to assess the impact of the clinical clerkship in obstetrics and gynecology on medical student IUD knowledge and attitudes.In this prospective cohort study, students at seven diverse US medical schools were surveyed at the start and completion of their obstetrics and gynecology clinical clerkships regarding IUD exposure, knowledge and attitudes. Subject responses were compared pre- and postclerkship.One hundred six students returned completed paired surveys (response rate 82%). The preclerkship mean knowledge percent correct (54%, SD 17%) increased significantly at postclerkship assessment (72%, SD 18%) (p<.0001). The mean attitudes score also increased significantly from pre- (34%, SD 31%) to postclerkship (59%, SD 26%) (p<.0001).US medical student IUD knowledge and attitudes are significantly improved through the obstetrics and gynecology clerkship. However, significant gaps in knowledge persist postclerkship.