The effects on sexual behavior in patients with chronic hepatitis C treated with IFN alpha plus ribavirin is an understudied field. The aim of our study was to evaluate this treatment on sexual behavior. We enrolled 170 male patients affected by chronic hepatitis C that received three MIU intramuscular leukocyte Interferon alpha plus Ribavirin thrice a week for 12 months. We assessed IFN influence by using the responses to International Index of Erectile Function (IIEF). The baseline values of each IIEF score were compared to those obtained at the end of months 1, 3, 6, and 12 as well as at the end of the follow-up period. At the end of month 1, we detected a significant reduction of IIEF scores with respect to basal values, for all administered items. These values were similar to those found at the end of month 3 for almost all parameters, being increased in only the scores of erectile function. At the end of treatment, all scores appeared reincreased, but only mean score of erectile function appeared similar to pretreatment value. The organism adapts itself in someway to the action of cytokine. Psychological influence of IFN on the patients could justify the partial impairment of sensation linked to sexual behavior. Our study provided some more information in quantification and qualification of sexual disturbances related to IFN plus Ribavirin administration in the treatment of chronic hepatitis C.