The aim of this study was to evaluate the potential relationship between self-reported sexual dysfunction, sexual behavior, and severity of addiction of drug users. A cross-sectional design study was conducted at an inpatient addiction treatment unit in Sao Paulo, Brazil, with a sample of 508 male drug users. Sociodemographic data, sexual behavior, and severity of dependence were evaluated.The prevalence of sexual dysfunction was 37.2% and premature ejaculation was 63.8%. Men with sexual dysfunction presented from moderate to severe level of alcohol, tobacco, and other drugs of dependence. The findings from this study are particularly relevant identifying those sociodemographic factors, severity of drug use, and sexual behavior are related to men who experience sexual dysfunction. Health promotion and motivational interventions on sexual health targeted to male drug users can contribute in reducing these at-risk behaviors. More interdisciplinary research is desirable in future in considering men’s sexual health.