OBJECTIVES: To estimate the number of men in the U.S. military who are gay, bisexual, or other men who have sex with men (MSM) to inform the development of military and other federal policies. STUDY DESIGN: We analyzed data from the National Surveys of Family Growth to estimate the number of U.S. men who were gay, bisexual, or MSM, and who had served in the military, compared to those who did not serve. We stratified using hierarchical categories of gay, bisexual, and other MSM to compare proportions in the military and general population. RESULTS: We found that 4.23% of men self-reported as gay, bisexual, or other MSM among men who served in the military, compared to 4.14% among men who had not served (p = 0.93). When stratified, we found that 0.78% self-reported as gay among men who served in the military, compared to 2.12% among men who had not served (p<0.001). CONCLUSIONS: The proportion of men who identified as a gay was lower in the military than in the general population. This finding might have been influenced by historical military policies related to sexual orientation.