Acute pancreatitis (AP) is a local inflammatory response with systemic effects and an adverse evolution in 20% of cases. Its mortality rate is 5–10% in sterile and 15–40% in infected pancreatic necrosis. Infection is widely accepted as the main reason of death in AP. The evidence to enable a recommendation about antibiotic prophylaxis against infection of pancreatic necrosis is conflicting and difficult to interpret. Up to date, there is no evidence that supports the routine use of antibiotic prophylaxis in patients with severe AP. Treatment on demand seems to be the better option, avoiding excessive treatment and selection of bacterial. In infected acute pancreatitis, antibiotics of choice are imipenem, meronem or tigecycline in patients allergic to beta-lactams. Also fluconazole must be given in determinate clinical situations.