Our study examined the impact of heroin on frontal executive functioning in three cognitive domains, namely attention, impulse control, and mental flexibility and abstract reasoning. It was hypothesized that heroin addiction would lead to deficits in these three cognitive domains. Fifty-five participants, 30 heroin addicts, and 25 normal controls were invited to participate in this study. Each participant was individually interviewed for demographic data and tested by the selected neuropsychological measures. The findings indicate that heroin addiction has a negative effect on impulse control, while attention and mental flexibility/abstract reasoning ability were not affected.