As part of the first quantitative study of men who have sex with men (MSM) and HIV/ AIDS in Spain, anonymous, self-administered questionnaires were distributed via gay/lesbian organization mailings, bathhouses, and sex shops in Barcelona. We analyzed 547 gay/bisexual men along self-reported HIV testing history-i.e. untested, previously tested HIV-, and previously tested HIV +. Eleven variables discriminated significantly between the three groups in multivariable analysis. HIV- men were over-represented in the mailing subsample. While untested men exhibited potentially protective behaviors (e.g. least likely to have had stable and casual sex partners with HIV/AIDS and to practice anal intercourse), they were also least likely to be out with their homosexuality and most likely to never use condoms when they practiced anal intercourse. HIV + men were most likely to report insertive and receptive anal intercourse with a condom and least likely to practice insertive anal intercourse without a condom in the past month, yet they were also most likely to report the highest interpersonal barriers to safer sex, recent cocaine use with sex, meeting sex partners in public restrooms, and recent episodes of STD. A potentially volatile combination of higher sexual activity (e.g. more sex partners and casual sex activity) coupled with the presence of safer sex barriers (e.g. poor scores on indices measuring safer sex disposition, elevated drug use accompanying sex) was evidenced among HIV + men. There were no statistically significant differences between the three groups for anal intercourse without a condom, but with 37.5% of this collective reporting one such episode in the past month, all groups can be considered equally risky. Against the backdrop of a 20.5% self-reported HIV prevalence, there is considerable need for enhanced prevention efforts among gay/bisexual men in general and targeted strategies among HIV + men in particular.