A case of drug-associated immune hemolysis in a patient taking tolmetin for arthritic pain is described. Serologic tests showed that in the absence of tolmetin, the patient had a negative antibody screening test but a strongly positive direct antiglobulin test. An eluate prepared from the patient's red cells caused agglutination of all cells tested. However, addition of tolmetin revealed a high-titered tolmetin-dependent antibody in the patient's serum; the addition of tolmetin did not affect the results obtained with the eluate. within 3 months after the patient discontinued tolmetin, his hematocrit had increased to 45 percent, and his jaundice and bilirubinuria had disappeared. These results are similar to those described for zomepirac, another of the group of nonsteroidal anti-inflammatory medications.