The Okun tribe, numbering about a million persons, accepts sexual relations between men and wives of their male kin. We identified and used features of spouse sharing that affect reproductive health to develop an interactive, community-based intervention. The intervention promoted discussion of spouse sharing as a risk factor in HIV/AIDS transmission, knowledge of AIDS/sexually transmitted diseases (STDs), perception of risk and alternative behaviors to avoid contracting HIV/AIDS. The intervention effects were evaluated using data collected in baseline and follow-up surveys in May 1999 and June 2000 among 1018 sexually active respondents in two sets of Okun communities - one with and the other without intervention. The intervention significantly increased knowledge of HIV/AIDS, perception of risk of contracting the disease and the intention to discontinue spouse sharing in the intervention communities. Those who perceived themselves at risk of contracting HIV/AIDS were more likely to express intention to discontinue spouse sharing (odds ratio 2.87) than those who did not. It was recommended that future community-based interventions to address traditional practices that could transmit HIV/AIDS should address the aspects of the practice that could transmit the disease and actively involve the people to make impact.