Background: Sexual and health-seeking behaviors are important components of sexually transmitted disease (STD) control. Goals: To generate data for improved STD prevention and care, and to assess sexual behavior and relevant health-seeking behavior. Study Design: A questionnaire to elicit social, demographic, healthcare-seeking, and sexual behavior information was administered to 471 patients attending the referral clinic for STDs in Nairobi, Kenya. Results: A large proportion of the patients had sought treatment in public and private sectors before attending the clinic for STDs. Women waited longer than men to seek medical care. In addition, women more than men engaged in sex while symptomatic, mostly with their regular partner. Condoms were used rarely during illness. In their self-reports, 68% of the men admitted to having extramarital affairs, and 30% to paying for sex, yet they blamed their wives for their STDs. Conclusion: Health education messages in Kenya need adaptation to improve health-seeking behavior and safe sex practices.