Background: Methadone or buprenorphine maintenance therapy is an effective treatment for opioid dependence. Since the satisfaction of patients under methadone maintenance treatment (MMT) plays an important role in their therapeutic success, it seems important to evaluate the satisfaction of methadone usage using multidimensional psychometric tools. Objectives: The current study aimed to investigate the psychometric properties of the Persian version of the Treatment Satisfaction Questionnaire for Medication (TSQM) version II. Patients and Methods: This cross‑sectional study was carried out on 288 opioid-dependent patients of Shahid Beheshti MMT clinic in Kerman, Iran, selected using the convenience sampling method. The data were collected using a questionnaire containing the demographic characteristics of the participants and the Persian version of the TSQM version II containing 11 items in four subscales of effectiveness, side effects, convenience of use, and overall satisfaction. The sum of the scores of each subscale is displayed as a number from 0 to 100. The face and content validity of the questionnaire was confirmed. The construct validity was assessed using exploratory factor analysis (EFA) and confirmatory factor analysis (CFA). The internal consistency and repeatability of the TSQM version II were determined using Cronbach’s alpha and test-retest methods, respectively. LISREL software (version 8.8) and SPSS software (version 20.0) were used to analyze the data. Results: The sample with the male majority of 85% had a mean age of 46.24 ± 11.5 years. As a measure of internal consistency, Cronbach’s alpha of the Persian version of the TSQM version II was 0.8. The repeatability of the questionnaire using the test-retest method was calculated at 0.9. The EFA revealed the adequacy of sampling and justifiability of the analysis (Kaiser‑Meyer‑Olkin = 0.82, P = 0.001, χ2 = 1507.02, df = 28). In CFA, the goodness of fit was at an appropriate level. Conclusions: The TSQM Persian version can be used as an effective and consistent tool to assess treatment satisfaction in clinical settings.