Human immunodeficiency virus type 1 (HIV-1) epidemiology among residents of a rural agricultural plantation in Kericho, Kenya was studied. HIV-1 prevalence was 14.3%, and was higher among women (19.1%) than men (11.3%). Risk factors associated with HIV-1 for men were age (>or=25 years), marital history (one or more marriages), age difference from current spouse (>or=5 years), Luo ethnicity, sexually transmitted infection (STI) symptoms in the past 6 months, circumcision (protective), and sexual activity (>or=7 years). Among women, risk factors associated with HIV-1 were age (25-29 years, >or=35 years), marital history (one or more marriages), age difference from current spouse (>or=10 years), Luo ethnicity, STI symptoms in the past 6 months, and a STI history in the past 5 years. Most participants (96%) expressed a willingness to participate in a future HIV vaccine study. These findings will facilitate targeted intervention and prevention measures for HIV-1 infection in Kericho.