Background: Acute pancreatitis is defined as an acute inflammation of the pancreatic parenchyma caused by activated pancreatic enzymes for a variety of reasons. The present study was conducted to assess red cell distribution width and its ratio to total serum calcium and platelet in acute pancreatitis patients. Materials & Methods: 84 patients of acute pancreatitis of both genderswere divided into 2 groups. Group I was severe and group II was mild acute pancreatitis. Each group had 42 patients. Organ failure of at least one organ system (defined as SBP <90 mmHg, PaO2 < 60, and creatinine >2.0 mg/dl following dehydration) and the appearance of local complications such necrosis, pseudocyst, or abscess were the criteria for severity in acute pancreatitis. RDW at 24 hours (RDW24h) and RDW at 0 hours (RDW0h) were assessed. Additionally assessed were the RDW0h-to-total serum calcium ratio, the RDW0h-to-platelets ratio, the Ranson score, and the BISOP score. Results: Group I had 22 males and 20 females and group II had 18 males and 24 females. The mean RDW at 0 hour in group I was 15.4% and in group II was 13.7%. RDW at 24 hours in group I was 14.1% and in group II was 12.6%. RDW 0h -to- total serum calcium ratio was 1.5 in group I and 1.2 in group II. RDW 0h – to - platelets ratio in group I was 0.08 and in group II was 0.04. The difference was significant (P< 0.05). The mean Ranson score in group I was 2.7 and in group II was 2.1. The mean BISOP score in group I was 2.2 and in group II was 1.3. The difference was significant (P< 0.05). Conclusion: In addition to the Ranson and BISOP scoring systems, red cell distribution width is a reliable indication of acute pancreatitis.