The male marriage squeeze in China may increase the prevalence of male same-sex sexual behaviors among unmarried male migrants who lack stable female sexual partners. The same-sex sexual behaviors among unmarried male migrants appear to be at high risk of transmission of human immunodeficiency virus (HIV) and sexually transmitted infections (STIs), mainly because of a lack of knowledge of these diseases. Using data from the "Survey on Reproductive Health and Family Life of Migrant Male Bachelors in Urban Areas" conducted in Xi'an City, Shaanxi Province, in December 2009 and January 2010, this study compares same-sex sexual behaviors of unmarried with that of married male migrants (including married but separated men who are migrating without their spouse or partner and cohabitating men who are migrating with their spouse or partner). It is reported that the prevalence of same-sex sexual behaviors among unmarried males reaches 11%, more than twice the 5.1% reported by married but separated men and thrice the 3.8% reported by cohabitating men. It also appears that the same-sex sexual behaviors is significantly associated with men's attitudes toward same-sex sexual behaviors (odds ratio = 1.59, p < .001), toward life-long bachelorhood (odds ratio = 1.35, p < .01), and with marital status (odds ratio = 0.37, p < .01). The frequency of condom use appears to be higher among unmarried men than among men who are married, whether or not they migrated with their wives, and is significantly associated with scores on knowledge about HIV/AIDS (estimated coefficient = .12, p < .001) and STIs (estimated coefficient = .22, p < .01). It is also associated with the likelihood of same-sex sexual behaviors (estimated coefficients = .83, p < .01) and marital status (estimated coefficients for married but separated = -.50, p < .05; estimated coefficients for cohabitating = -.77, p < .001).