With the significant increase in the computer and internet usage, the new concept of addiction to internet games is now considered as a new psychiatric disorder. The evidences have demonstrated that the internet gaming disorder is similar to drug addiction in terms of neurology, but just a few researches has been done in terms of brain functions. The aim of this project is to compare Inhibitory control and risky decision making among heroin and methamphetamine users, internet gaming disorders and normal people. To do so 180 men participants (45 persons in each group) were selected via simple nonrandom or convenience sampling. Subjects of the study were evaluated using go/no go and Balloon Risk Taking Task (BART) test. For analyzing the results multivariable analyze of variance was used. Results showed that inhibitory control in both substance abuse disorder and internet gaming disorder was significantly lower than normal group (P<0.001). Although internet gaming disorder group showed better performance in comparison with substance abuse disorder group. (P<0.001) Moreover, risky decision-making in internet gaming disorder group was similar to substance abuse disorder group and was significantly higher than normal group (P<0.001). Generally, there are relative similarity in impulsivity parameters particularly in risky decision-making and inhibitory control between internet gaming group and substance abuse group. This can lead to continue taking drugs or online gaming despite of their annoying consequences.