The study examined whether closing of a methadone maintenance clinic in Israel on the Sabbath was associated with adverse patient outcomes. One take- home dose of methadone was given to all patients for that day regardless of whether they had earned take-home privileges. No difference was found in dropout rates for the six-month periods before and after Saturday closure was initiated. Results of random, twice-weekly urinalyses for all patients did not indicate increased use of heroin. The findings suggest that closure of a methadone clinic at least one day a week does not jeopardize patient outcome. Cutting hours of operation would reduce workload and enable clinics to function more economically.