Introduction: Genital infections with human papilloma virus (HPV) are the most common sexually transmitted disease in the United States. Several predisposing factors are known for this infection. So far, no studies on the risk factors and clinico-epidemiologic aspects of genital warts in Iran have been reported. So, we performed this study to evaluate epidemiologic aspects of anogenital warts in Mashhad, Iran. Methods: In this case-control study, 100 patients with genital warts who referred to the dermatology clinic of Imam-Reza hospital (August 2005 - August 2007) and 100 age, sex and marital status matched healthy controls were included. Clinical and epidemiologic data were recorded using designed questionnaire. Finally, chi-square and t-student tests were used for statistical analysis. Results: Male to female ratio was 0.87. The majority of the patients aged 30-39 years. Glans of the penis and posterior fourchette were the most common sites of involvement. Positive history of sexual contacts and sexual transmitted diseases (STDs), use of condom, pregnancy, addiction, use of swimming pools and number of marriages were significantly different in two groups. Conclusion: Younger age, higher number of marriages, having several partners, non-traditional sexual behavior, pregnancy, use of swimming pools, refuse to use condoms, history of other STDs, immune suppression, use of immunosuppressive drugs and topical steroids were the main risk factors of anogenital warts in this study.