This study focuses on patients with severe acute pancreatitis complicated by organ failure within the initial phase of the disease. Data of 158 patients with severe acute pancreatitis (SAP) admitted to hospital within 72 hours after onset of symptoms were prospectively documented and analyzed for the occurrence of early severe acute pancreatitis (ESAP). ESAP was defined as presence of organ failure (OF) at admission. Forty-seven (30%) patients had ESAP, compared with 111 patients without OF (SAP group). In a multivariate analysis, the main factor predisposing to ESAP was the presence of extended pancreatic necrosis (odds ratio, 3.8), whereas biliary pancreatitis was associated with a slightly lower risk compared with alcoholic pancreatitis (odds ratio, 0.34). Compared with SAP, patients with ESAP more frequently developed intractable organ failure, which posed the indication for surgical treatment. Surgical necrosectomy due to progressive OF had to be performed in 89% of the ESAP patients and in 60% of the SAP patients. The incidence of infected pancreatic necrosis did not differ between both groups (23 vs. 21%). Mortality was significantly higher in ESAP (42 vs. 14%; p = 0.0003). ESAP is characterized by the presence of extended pancreatic necrosis and a complicated clinical course. Intractable organ failure is a frequent finding. Given the poor prognosis of ESAP, these patients should be treated in specialized intensive care units.