We report an unusual case of transfusion-transmitted
malaria which remained undiagnosed for several months
in an Italian woman splenectomised and polytransfused for thalassaemia major. The infecting species was <i>Plasmodium malariae</i>, and the patient developed acute renal failure, severe thrombocytopenia, and hepatic failure. Treatment with chlorochine was followed by a slow, but complete recovery of renal function.