The aims were to identify predictors of treatment retention in an Israeli methadone maintenance treatment (MMT) clinic, and to compare the findings to other international settings. We prospectively studied 492 patients admitted since 1993 through 10 years to an Israeli MMT clinic associated with a university-affiliated tertiary care medical center. Analyses (Kaplan Meier and Cox regression) included methadone dose and urinalysis results (for methadone, cocaine, opiates, benzodiazepines, THC, amphetamines) of each patient in the first month and after 1 year in treatment (or during the last month if the stay was >3 months and <1 year) and patients' characteristics (modified ASI). The 1-year retention rate was 74.4%; 65.8% stopped opiate abuse after 1 year in treatment. On admission, 13.6% of patients had used cocaine: there was a net decrease of 61.6% after 1 year. Factors predicting prolonged retention in MMT treatment (Cox regression) were daily methadone dose of 100mg or greater, negative urine for opiates after 1 year, and being a parent on admission. We conclude that our good outcome results (high rate of retention after 1 year (74.4%), high proportion of opiate abuse cessation (65.8%), and net reduction in cocaine abuse, similar to normal standards in other MMT clinics elsewhere in the world, justify the expansion of the MMT clinic network in Israel in order to make treatment available to all those who need it. A protocol favoring higher methadone dosage as appropriate is recommended.