The Coombs (antiglobulin) test as applied to erythrocytes has been especially of value in the identification and study of isoimmune states1,2and in acquired hemolytic anemia3,4in which an autoimmune state has been proposed.5,6Recently Harris7described an additional application of the Coombs test to erythrocytes which was dependent on humoral factors in the patient's serum plus the trivalent antimony compound stibophen (Fuadin). This phenomenon, associated with a hemolytic state due to multiple contacts by the patient with the drug stibophen, may be compared with the drug-dependent agglutination of platelets described by Ackroyd8,9in the thrombocytopenia induced by allylisopropylacetylcarbamide (Sedormid) and varified for quinidine10-12and quinine.13It is also of interest that the agglutination of leukocytes dependent on serum factors and a drug, similar to Ackroyd's phenomenon for platelets, has been described.14 In the present report we wish to record the encounter of a positive Coombs test for