This study evaluates the outcome of a mandatory, clinic wide, structured contingency contracting system in a methadone maintenance program. The system involved weekly urine screening and placement on written individualized contracts for any of 106 male patients who displayed illicit drug use. Methadone dose decreases were the penultimate and detoxification and discharge the ultimate contingencies for unremitting drug use. Sixty subjects (56.6%) received contracts and 36 (35%) eventually left treatment. The contracts did not decrease the overall number of positive urines for the contract subjects, but opiate use did decrease significantly for subjects on more stringent contracts.