['To investigate the clinical usefulness of procalcitonin (PCT) for guiding duration of antibiotic therapy in patients with severe acute pancreatitis (SAP).', 'A total of 71 patients with confirmed severe acute pancreatitis from March 2009 to September 2011 in the Department of Critical Care Medicine of Huizhou Municipal Central Hospital, Guangdong, China were enrolled in this study. Procalcitonin was measured daily by a semi-quantitative immunoassay in the study group. Patients were randomly assigned into 2 groups including a PCT-guided group (study group) and a prophylactic antibiotic therapy (control group). Antibiotic therapy in the study group was not applied until clinical signs and symptoms of infection appeared (PCT value was >0.5ng/ml). We discontinued the antibiotic therapy if clinical signs and symptoms of infection improved and PCT was <0.5ng/ml over 3 days. In the control group, antibiotic therapy was administrated for 2 weeks, or antibiotic therapy was continued because of confirmed infection until clinical signs and symptoms of infection disappeared over 3 days.', 'In the study group (35 patients), the duration of antibiotic therapy and hospitalization was significantly shorter than the control group (36 patients) (10.89+/-2.85 versus 16.06+/-2.48 days, p<0.001, and 16.66+/-4.02 days versus 23.81+/-7.56 days, p<0.001) without negative clinical effects and the cost of hospitalization was significantly lower.'] Is procalcitonin a good tool to guide duration of antibiotic therapy in patients with severe acute pancreatitis . A randomized prospective single-center controlled trial?