Patients with autoimmune haemolytic anaemia (AIHA) frequently have anaemia of sufficient severity as to require a blood transfusion. However, it is impossible to find compatible blood when, as is frequently the case, the autoantibody in the patient's serum reacts with all normal red blood cells. Further, the autoantibody may mask the presence of a red cell alloantibody capable of causing a haemolytic transfusion reaction. Optimal patient management in this clinical setting requires special compatibility test procedures in the transfusion service laboratory. Equally important is that clinicians must understand the principles of the compatibility tests performed. Provided appropriate compatibility tests are performed, the indications for transfusion in patients with AIHA are not significantly different than for similarly anaemic patients without AIHA. Communication between clinicians and laboratory personnel are important to review the urgency of transfusion and the compatibility test methods used to select the optimal unit of red blood cells for transfusion.