Studies of treatment outcome among addicts have focused on demographic factors and treatment modalities. This follow-up of treated narcotic addicts in Laos examines these two variables, plus the role of community factors in determining outcome.Three research methods were used. First, addicts readmitted within 365 days after discharge were compared with addicts not readmitted. Second, 25 addicts were selected for follow-up at 1 year post discharge; they were chosen from rural areas in order to represent addicts not likely to return to the treatment facility for readmission. Finally, 10 villages and towns were surveyed to assess the percentage of addicts seeking treatment and the percentage remaining abstinent.The study of readmitted patients and the survey of readdicted patients failed to show differences for sex, age, ethnicity, marital status, or type of opiate used when compared to non readmitted or abstinent patients. In contrast, the field survey showed that the proportion of addicts from a village or neighborhood coming to treatment was highly correlated with treatment outcome. Where more than two thirds of addicts from a given locality went for treatment, abstinent rates were high (i.e., 81 to 100 per cent). Where less than one third of addicts from a given locality went for treatment, abstinent rates were low (i.e., 0 to 25 per cent). Between these two extremes were two large towns where the abstinent rates were intermediate (i.e., 42 and 50 per cent). In these latter areas, abstinence was associated with: a) contacts with other ex-patients who were abstinent; and b) frequent contact with a person or institution interested in the person's continuing abstinence.Unexpectedly, demographic and clinical variables were not associated with treatment outcome in this study. By contrast, social variables in the addict's own community were highly correlated with outcome. These data indicate the need for study of outreach activities, including negotiation with community leaders and with groups of addicts themselves before initiating treatment activities.