The purpose of this study is to detect the prevalence of sexual dysfunction and also to investigate possible risk factors that may cause sexual dysfunction in Turkish men. We developed a Web-based survey. In total, 3185 invitations to complete the survey were e-mailed and 2288 individuals submitted responses (72%). The men were interviewed in person, using the Florida Sexual History Questionnaire (FSHQ) Turkish version, and sexual dysfunction was assessed by this questionnaire. male sexual dysfunction (MSD) was evaluated with FSHQ. According to the FSHQ Turkish version, sexual function domains included sexual desire, sexual development, intercourse, erection, ejaculation, and satisfaction. According to the FSHQ score, 43.3% reported on MSD (FSHQ scorep95). The prevalence of MSD was 56% in the ages of 15-24 y, 35% in 25-34 y, 26% in 35-44 y, 40% in the ages of 45-54 y, and 72% in the ages of 55-60 y. MSD was detected as a desire problem in 7.3%, sexual development problem in 54.7%, intercourse problem in 50.3%, arousal/erectile problem in 59.7%, orgasm/ejaculation problem in 52.7%, and satisfaction problem in 59.7%. The age-adjusted risk of developing MSD was higher for men with smoking, lower education, and chronic medical diseases. In conclusion, the prevalence of MSD is 43.3% in Turkish men. The most important risk factor for MSD is smoking. In addition, the presence of younger and older age, chronic medical diseases, and lower educational level are important risk factors that may cause MSD.