Severe acute pancreatitis (SAP) has many similarities with sepsis syndrome and septic shock. The hemodynamic features are virtually indistinguishable in each of these conditions. Septic complications of SAP are usually late manifestations, although sterile pancreatic necrosis is observed early in acute pancreatitis. In patients with SAP, it is extremely important to understand possible septic complications, methods of their diagnosis and treatment. The overall mortality of patients with SAP is about 20%. Secondary pancreatic infection and sepsis develop in 40-70% of patients with 80% mortality. Pancreatic infection is caused by bacterial/ fungal contamination of pancreatic necrosis. Infection is usually recorded in the second (25%) to fourth (70%) weeks of the disease. The frequency of secondary infection and sepsis correlates with the degree of pancreatic necrosis. Sepsis and sepsis-related multiple organ failure are the cause of mortality in approximately 50% of patients. Prevention of infection and sepsis by systemic antibiotics is considered the mainstay of therapy for SAP. However, the effect of antibiotic prophylaxis has not yet been proven. Patients with SAP at the stage of purulent-septic complications are a heterogeneous group, but from the point of view of the pathogenesis of the disease, they have a significant number of common features. Similar features between SAP at the stage of purulent-septic complications and sepsis make SAP an excellent model for studying the general pathogenesis of sepsis.