Acute pancreatitis is a complex and potentially severe disease. The incidence of the disease is on the rise, primarily because of an increased exposure to risk factors as well as an increased life expectancy. There are numerous causes of acute pancreatitis of which the most common are cholelithiasis and alcoholism. The exact and complete pathogenetic mechanism of acute pancreatitis is still not entirely known. However, recently there has been a significant shift in the perceiving of this mechanism. The damage to the acinar cell and the subsequent inflammatory cascade is the basic process in this new concept. Acute pancreatitis can be mild to moderately severe (interstitial) or severe (necrotizing). The basic symptom of either degree of the disease severity is an intensive pain, most often localised in the epigastrium, while other symptoms vary according to the disease severity. Doctors today have numerous diagnostic "tools" at their disposal, but the thorough physical examination is still of a paramount importance. Considering that, measuring serum lipase and amylase concentrations is still the most often used diagnostic method, while the CT-scan is regarded as the "gold standard" for a reliable diagnosis of severe acute pancreatitis. Assessing the disease severity is very important and there are numerous systems which can be used for the accurate assessment of the disease severity, such as the Ranson's criteria and the APACHE II score. Although the specific therapy depends on the disease severity, the main therapeutic goals are universal and they are: limiting systemic complications, the prevention of development of pancreatic necrosis and the prevention of infection when the necrosis has already occurred. Today, the therapy is based on the supportive care and the prevention of complications. Complications of acute pancreatitis can be local and systemic. The most dangerous local complication is the infected necrosis, whilst the most dangerous systemic complication is a multi-organ failure. The prognosis of the disease depends on the disease severity as well as the presence of complications. Acute pancreatitis with the developed infected necrosis has the worst prognosis with an overall mortality of up to 25%.