Objective There are contradicting reports regarding the relationship between cannabis use and male sexual functions with almost no data about synthetic cannabinoids (SC) and its effect on male sexual functions. This study investigates psychological concerns related to male sexual functions among cannabis and SC users. The research aims to assess different sexual functions and aspects of sexual psychopathology in cannabis and SCs dependent men compared to controls. Method Thirty male patients with cannabis dependence, thirty male patients with SCs dependence and thirty matched controls from the outpatient clinic of Kasr Al Ainy hospital, Egypt, were assessed using Structured Clinical Interview for DSM-IV TR Axis I Disorders (SCID-I), International Index of Erectile Function (IIEF), and Sexuality scale. Results The means of IIEF questionnaire in the cannabis and SC group were significant lower than the means of the control group ( P < .001) except the orgasmic function in cannabis group ( P = .052). In the SCs group, sexual depression was higher and preoccupation lower than the cannabis ( P < .020; P < .003, respectively) and control groups ( P < .001; P < .001, respectively). The duration and dose of intake of cannabis and SCs correlated significant with sexual esteem, sexual preoccupation and all domains of IIEF. Conclusion Cannabis and SC dependence were associated with lower erectile function, sexual desire, intercourse satisfaction and overall satisfaction, and lower orgasmic functions in the SC group than controls. Both groups showed higher sexual depression, lower sexual esteem and sexual preoccupation than controls. SC has a higher negative impact on male sexual functions and psychopathology than cannabis.