A 42-year-old leukaemic black male developed shortness of breath, itching, hot flushes, substernal pain, marked hypotension, and cardiorespiratory arrest after the infusion of 50 ml of pooled platelet concentrates. The patient had had one previous and uneventful red blood cell transfusion. Serologic studies of this patient's post-transfusion serum showed the presence of an antibody against one denatured IgA2 protein with the phenotype A2m(1 + 2-). All of the platelet donors were A2m(1) positive. The patient was successfully transfused with platelets from donors with the phenotype A2m(1 - 2+). Although 35.8% of Blacks and 30.0% of Chinese are A2m(1) negative, this is the first reported transfusion reaction associated solely with the occurrence of a possible anti-A2m(1) in an individual of the type A2m(1 - 2+).