We have experienced a case of incompatible blood transfusion during general anesthesia in which 300ml of improperly typed blood were transfused. Upon discovery of the error, the transfusion was discontinued and the patient was immediately, carefully and aggressively treated with proper fresh blood, plasma expander(Rheomacrdex-D), fluids(Hartmanns solution and 10% dextrose in water) and drugs (Solu-Cortef 300 mg, furosemide 400 mg, 20% manitol 500 ml, digoxine 0.5 mg, morphine 15 mg). The free hemoglobin in the plasma and urine and blood gas of the femoral or radial artery were rnonitorecl throughout the resuscitative procedure. It is felt that accidental incompatible blood transfusion of more than 300 ml should be preventable and that the patients life may be saved without serious complications with immediate and proper management.