Objective: The aim of this study was to determine the effectiveness of acceptance and commitment therapy (act) in reducing total, cognitive, motor, and nonplanning impulsiveness among methamphetamine-dependent patients. Method: In the present study, a single-case experimental design of a linear asynchronous baseline was used. Research tools, such as structured clinical interviews, demographic characteristics questionnaire, urine test, Barrett Impulsiveness Scale, and individual protocol of ACT for substance abusers were used for data collection. The obtained results were evaluated using visual imaging, permanent change index (RCI), recovery percentage, meaningful clinical improvement, and operational measurements. Results: The obtained data showed that total impulsiveness and its subscales in patients were statistically, clinically, and operationally significant. Conclusion: Acceptance and commitment therapy (ACT) is effective in reducing the total, cognitive, motor, and nonplanning impulsiveness in methamphetamine-dependent patients.