Direct Antiglobulin Tests (DAT) as well as a number of immunological parameters (immunoglobulin levels, latex fixation, VDRL) were studied in 168 narcotic-addicted patients. Of these, 94 were untreated narcotic addicts (Group I), 61 were methadone maintained patients (Group II), and 13 had completed successful detoxification with methadone and were drug-free (Group III). Weakly positive DAT were detected in 2.1 per cent of individuals in Group I, 18 per cent in Group II, and 15 per cent in Group III. The reactions were usually transient. A number of other immunological aberrations were also present in individuals of all three groups, but there was no correlation between these parameters and the positive direct antiglobulin reactions.