This article deals with an attempt at evaluating the success of a drug-free narcotic treatment program in New York City through a follow-up study of 300 ex-clients of the program. Two hundred ex-clients out of the 300 target population were actually interviewed. The number of months the clients had remained in the treatment program was found to be a key factor in the outcome of the program. The length of time in the program was itself highly dependent upon the client's background: the higher the pretreatment pathology the lower the chance of treatment success.