This paper seeks to determine the client's compliance level towards Methadone Maintenance Therapy (MMT) and identify its associated factors. A cross sectional study was conducted from June to September 2007 where 288 samples were interviewed. The outcomes were divided into good compliance and partial compliance categories. Overall client's compliance level is good at 86.1%. There are significant difference between mean age of groups (t = -2.041, p = 0.04); and significant associations of job's status (chi2 = 9.54, p = 0.008); client's confident score (t = -3.12, p = 0.023), client'ssocial function score (t = -2.308, p = 0.002) and client's social function level (chi2 = 5.43, p = 0.02) with compliance toward program. With multivariate analysis, only client's age, client's confidence score and client's job status were related to compliance status. It was concluded that there is high compliance rate among client's who received the program. Younger clients, low scores on client's confident and social function, and clients with unsteady jobs are at risk not to comply with treatment.