Little is known about national trends in sexual behavior among MSM in the US. Data from the 2002 and 2006-2010 National Survey of Family Growth were used to compare sexual behaviors of sexually active MSM. Mean number of recent male partners significantly decreased from 2.9 in 2002 to 2.1 in 2006-2010 (P = 0.027), particularly among young MSM. Other sexual risk behaviors did not change or decrease over time. Our findings that sexual risk decreased as HIV and syphilis increased among MSM suggest that factors in addition to individual-level sexual risk should also be examined in relation to recent disease increases.