Objectives: Previous studies have revealed the efficacy of methadone maintenance treatment (MMT). In this study, we intended to investigate clinical efficacy of the MMT and to compare the differences between dropout and remaining heroin users in the MMT. Methods: We conducted a retrospective chart review. We recruited 379 participants, and collected information of their social demography, medical assessments, and drug abuse history in medical records. Descriptive statistics using t-test, chi-square test were used. Results: We found that the rate of positive urine morphine analyses was decreased gradually by the continuing intervention of the MMT. Significant differences in dosage, positive urine analyses, attendance rates between the dropout and remaining group in treatment. But no significant differences were found in age, marital status and HIV sero-status between those two groups. Conclusion: Our study findings suggest that we need to identify patients who are apt to dropout during the early stage of the MMT, and offer support and counseling. We recommend that further research need to consider an applicable intervention for this population.