Pancreatitis has been described as a complication in about 1.7% to 2% of cases of thrombotic thrombocytopenic purpura (TTP) or hemolytic uremic syndrome (HUS), which has been generally attributed to the pancreatic vascular compromise. However, the reverse situation-the development of clinical features of TTP or HUS following the clinical and laboratory diagnosis of acute pancreatitis-is very rare. Other hematological abnormalities such as hypercoagulation, disseminated intravascular coagulopathy, changes in hematocrit, leukocytes, and thrombocytopenia also have been observed and correlated to the outcome of acute pancreatitis. The authors review the medical literature, describe different hematological abnormalities encountered in patients with pancreatitis, and discuss its pathogenesis.