To the Editor.— Preliminary results of treatment of heroin addicts with propoxyphene napsylate (Darvon-N) were recently reported.1Numerous reports have subsequently reached me that indicate propoxyphene napsylate treatment is spreading at a faster rate than current data on effectiveness and safety may warrant. Initial observations indicate that propoxyphene napsylate has minimal physical addiction liability, and low overdose and abuse potential. Consequently, this treatment has great appeal to many addicts, law enforcement agencies, and physicians. Despite early promise, however, clinical experience with propoxyphene napsylate treatment of heroin addicts is quite limited. As of Aug 1,1973, three Los Angeles programs have detoxified 280 heroin addicts, and an additional 92 addicts have been maintained on an out-patient basis with propoxyphene napsylate for periods ranging up to 300 days. Eight of the propoxyphene napsylate maintenance patients were directly transferred from methadone maintenance. Our detoxification schedule for in-patients is as follows: Daily medication is