Increasing use of long-acting methods of contraception, such as intrauterine devices (IUDs), has been recognized as a promising strategy to reduce the incidence of unintended pregnancy. While men may play an important role in promoting or discouraging contraceptive use, very little research has examined men's knowledge of and attitudes toward IUDs.We used data from the 903 men included in the 2009 National Survey of Reproductive and Contraceptive Knowledge to examine their awareness and knowledge of IUDs and other contraceptive methods by several individual-level characteristics.Men's awareness and perceived knowledge of IUDs is low in comparison to condoms and birth control pills. Men's perceived knowledge of IUDs was lower than their objective knowledge, as measured by true/false questions about IUDs, suggesting that men may be more knowledgeable of IUDs than they perceive. In the multivariate models, men who were uninsured [adjusted odds ratio (AOR), 0.4; 95% confidence interval (CI), 0.2-0.6], identified as Christian (AOR, 0.6; 95% CI, 0.3-1.0) and who had never had a sexual health visit (AOR, 0.6; 95% CI, 0.4-1.0) were less likely to have heard of IUDs. Among men who had heard of the method, Hispanic men were less likely (AOR, 0.2; 95% CI, 0.1-0.5) to be more knowledgeable of the method.Young men report low awareness of IUDs in comparison to other methods, and this varies by demographic characteristics including health insurance status. Family planning programs should consider targeted knowledge promotion for young men, with a focus on contraceptive methods besides condoms and oral contraception.Male partners are influential in contraceptive use, yet little research has examined their IUD knowledge. Our findings indicate that healthcare providers may play important role in increasing young men's knowledge of contraceptive methods, including IUDs. This study highlights the need to better incorporate young men into contraception research and programs.