The clinical courses of 75 patients with pancreatic pseudocysts documented by computed tomography (CT) were retrospectively reviewed. History, physical examination, laboratory findings and CT scan data were analyzed. The treatment regimen followed during the period spanning the review dictated nonoperative management for those patients with asymptomatic pseudocysts who were able to tolerate oral intake. Operative management was used only for patients with persistent abdominal pain or enlargement or complications of pseudocyst. Approximately one-half of the patients (n = 36, 48 per cent) were managed nonoperatively, and the remainder (n = 39, 52 per cent) were treated operatively. In the group managed nonoperatively, with a mean follow-up period of one year, 60 per cent had complete resolution of the pseudocyst documented roentgenographically, and 40 per cent had pseudocysts that remained stable or decreased in size. Only one pseudocyst-related complication developed in the nonoperative group. No pseudocyst-related mortality occurred in either group. The size of the pseudocyst was a significant predictor of the need for operative drainage. Pseudocysts greater than 6 centimeters in diameter required surgical treatment in 67 per cent, significantly more frequently (p less than 0.05) than the 40 per cent of patients who required operative treatment for pseudocysts less than 6 centimeters in diameter. We conclude that a large proportion of patients with pancreatic pseudocysts, without specific indications for operative treatment, can be safely managed nonoperatively, with careful clinical and roentgenographic follow-up study.