Opium addiction has been reported among virtually all large ethnic groups in Asia. Conspicuous by its absence has been any mention of addiction among the Lao, a people surrounded by poppy-growing tribal groups. A sample of Lao patient-addicts are here compared to expatriate Asian addicts in Laos. Lao and expatriate addicts show marked similarity in their sociodemographic profiles and patterns of narcotic use. Some differences in their recent use of narcotic drugs appear related to the greater cash income of the expatriate Asians and their greater access to heroin. No specifically 'cultural' factors for explaining ethnic differences in addiction have yet been identified.