Unfaithful individuals are less likely to practice safer sex than openly nonmonogamous individuals.

INTRODUCTION Given the prevalence and harm of sexually transmitted infections (STIs), there is a need to examine safer sex strategies in the context of romantic relationships and extradyadic sexual encounters. Sexual infidelity is associated with a variety of detrimental psychosocial outcomes; however, little research has addressed the sexual health ramifications of sexually unfaithful partners and members of other high-risk nonmonogamous lifestyles. AIMS To determine whether sexually unfaithful individuals or "negotiated nonmonogamous" individuals are more likely to engage in sexual health risk reduction behaviors during extradyadic encounters and with their primary partner. METHOD Data were collected via an anonymous Internet-based study. Several hundred sexually unfaithful individuals and individuals with a negotiated nonmonogamy agreement completed a sexual health questionnaire. MAIN OUTCOMES MEASURES Self-reported measures of risk reduction behaviors within the primary relationship and risk reduction behaviors during the extradyadic encounter were assessed. RESULTS Sexually unfaithful participants demonstrated significantly lower rates of protective sexual health behaviors both within their primary partnerships and during their extradyadic sexual encounters. Sexually unfaithful participants were also less likely to engage in frequent STI testing, and less likely to discuss safer sex concerns with new partners. CONCLUSIONS These data add to the literature on the negative effects of sexual unfaithfulness. Understanding rates of nonengagement in safer sex strategies will be helpful to those who lead efforts to increase condom use and other preventive STI measures.