Objectives: (1) Epidemiological characteristics of patients in methadone treatment center, Le Chan district, (2) Describe some factors related to adherence with Methadone treatment Methods: cross-sectional descriptive study, all 394 patients treated over 12 months from 2009 to 2011 at a Le Chan methadone treatment center selected. Interviewing patients, gathering information from medical records and consulting records. Analysis on SPSS software, 3.2.1 openepi, comparing dropout rates between groups based on X-squares algorithm. Results: The 394 patients treated with methadone in Le Chan district, Haiphong that mostly men (97.7 percent), aged 30-50 years (89 percent), living alone (49, 5 percent), married (31.2 percent) and education level is secondary school graduates (50 percent). Dropout rate 5 consecutive days was 22.1 percent of patients. Patients infected with HIV have a higher risk of dropping out of 1. 71 times compared with patients not infected with p 0.05. Patients with intent and suicidal behavior and received counseling 10 times have higher risk of dropping out of 10.93 times and 10.34 times compared with patients who did not have this behavior with p 0.001. No relevant differences and statistical significance between dropout rate and families with drug addicts, the side effects (constipation, sweating). Conclusions: Patients treated at the Methadone center is primarily male (97.7 percent), aged 30-50 years (89 percent), single (49.5 percent) and education level of the junior high school graduates (50 percent). Dropout rate is 22.1 percent of patients. Patients infected with HIV have a higher risk of dropping out of 1. 71 times compared with patients not infected with p 0.05. Patients with intent, suicidal behavior and receiving treatment advice 10 times have higher risk of dropping out of 10.93 times and 10.34 times compared with patients who did not have this behavior with p 0.001. No relevant differences and statistical significance between dropout and families with drug addicts, the side effects (constipation, sweating).