AIM: To study clinical characteristics and management of patients with early severe acute pancreatitis (ESAP). METHODS: Data of 297 patients with severe acute pancreatitis (SAP) admitted to our hospital within 72 h after onset of symptoms from January 1991 to June 2003 were reviewed for the occurrence and development of early severe acute pancreatitis (ESAP). ESAP was defined as presence of organ dysfunction within 72 h after onset of symptoms. Sixty-nine patients had ESAP, 228 patients without organ dysfunction within 72 h after onset of symptoms had SAP. The clinical characteristics, incidence of organ dysfunction during hospitalization and prognosis between ESAP and SAP were compared. RESULTS: Impairment degree of pancreas (Balthazar CT class) in ESAP was more serious than that in SAP (5.31+/-0.68 vs 3.68+/-0.29, P<0.01). ESAP had a higher mortality than SAP (43.4% vs 2.6%, P<0.01), and a higher incidence of hypoxemia (85.5% vs 25%, P<0.01), pancreas infection (15.9% vs 7.5%, P<0.05), abdominal compartment syndrome (ACS) (78.3% vs 23.2%, P<0.01) and multiple organ dysfunction syndrome (MODS)(78.3% vs 10.1%, P<0.01). In multiple logistic regression analysis, the main predisposing factors to ESAP were higher APACHE II score, Balthazar CT class, MODS and hypoxemia. CONCLUSION: ESAP is characterised by MODS, severe pathological changes of pancreas, early hypoxemia and abdominal compartment syndrome. Given the poor prognosis of ESAP, these patients should be treated in specialized intensive care units with special measures such as close supervision, fluid resuscitation, improvement of hypoxemia, reduction of pancreatic secretion, elimination of inflammatory mediators, prevention and treatment of pancreatic infections.