In 2008, CDC conducted an analysis of trends in diagnoses of human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) among men who have sex with men (MSM) in the 33 states that have had confidential, name-based HIV case reporting since at least 2001. This report summarizes the results of that analysis, which indicated that the number of HIV/AIDS diagnoses among MSM overall during 2001-2006 increased 8.6% (estimated annual percentage change [EAPC] = 1.5). During 2001-2006, an estimated 214,379 persons had HIV/AIDS diagnosed in the 33 states. Of these diagnoses, 46% were in MSM, and 4% were in MSM who engaged in illicit injection-drug use (IDU) (i.e., MSM and IDU). To reduce the impact of HIV/AIDS in the United States, HIV prevention services that aim to reduce the risk for acquiring and transmitting infection among MSM and link infected MSM to treatment must be expanded.