Hemolytic transfusion reactions (HTRs) remain one of the dreaded complications of transfusion-related morbidity and mortality. Here, we describe the diagnosis and management of acute HTR following transfusion of ABO-incompatible packed red blood cell under general anesthesia which manifested solely as acute intraoperative hematuria. A 65-year-old, diabetic male was scheduled for emergency re-explorative laparotomy in view of suspected anastomotic leak following subtotal gastrectomy. One unit of packed cell was transfused intraoperatively. Toward the end of surgery, hematuria was noted by the attending anesthesiologist, and the accidental bladder injury was ruled out by the surgeon. Transfusion of ABO-incompatible blood was spotted; direct Coombs test became positive. To mitigate the impact of incompatible blood, 1 L of 0.9% normal saline was administered. Mannitol 0.5 g/kg and furosemide 20 mg were administered every 8th hourly, and 1 ml/kg/h of urine output was targeted. Sodium bicarbonate (7.5%) 20 meq was administered intravenously to alkalinize the urine.