Six types of autoimmune hemolytic anemias have been described. Table 1 provides summary highlights for each type of AIHA. WAIHA accounts for the majority of cases, followed by CAIHA and DIAHA. In recent years, AIHA status post-BMT has been noted to occur more often than previously reported, particularly in T-cell-depleted graft recipients. The clinical presentation is diverse among the various types of AIHAs: WAIHA cases may require a complex treatment regimen if unstable hemolytic anemia is present, and often permanent remission is infrequent. In contrast, CAIHA in younger patients (status postinfection) is frequently asymptomatic and self-limiting. If AIHA is suspected in a patient with clinically significant presentation, it is important to communicate with the transfusion service since specific tests to confirm these diagnoses are not routinely done. Special procedures may be necessary to identify underlying rbc alloantibodies prior to transfusion. In a patient pre-operative for cardiopulmonary-bypass surgery, CAIHA antibody testing should be done. When found, pre-operative management may lessen the risk of serious consequences such as hemolysis, renal failure, and myocardial damage. AIHA associated in BMT recipients is frequently severe, and, in some cases may be refractory to treatment despite complex management strategies. Further studies are needed to acquire a better understanding of the pathogenesis of BMT-associated AIHA.