The purpose of this study was to identify men's co-responsibility in the negotiation process of dual protection, according gender, in their first and most recent sexual relationships, and their perception of the risk of STD/AIDS. We surveyed 750 males from 19 to 29 years of age in 2,250 randomly selected households in metropolitan Lima, Peru. The majority mentioned condoms as a contraceptive technique (95%). Their first sexual relationships occurred with a female friend, with a stable partner, or with a known woman. Almost half used some type of protection, principally condoms in order to avoid pregnancy, but their consistent and correct use was low. For 39.5%, the most recent sexual relationship was with a stable partner, a female friend or "known" woman, a wife, or a female co-resident. Dialogue about protection increased between the first and the most recent sexual relationships. The perception of risk of acquiring STD/AIDS was low, and they tended to use protection only with an "unknown partner".