Incidental pancreatic cysts are frequently detected, but no appropriate management guidelines have been issued for their management because their natural history is relatively unknown. The aim of this study was to investigate their long-term clinical outcomes. Pancreatic cysts detected from 1998 to 2004 were retrospectively reviewed in patients followed up for more than 3 months. A total of 182 patients with incidental pancreatic cysts (initial mean size, 1.8+/-1.1 cm) underwent follow-up for an average of 35.4 months. An age>/=60 years was found to be associated with an increase in cyst size, with an odds ratio of 2.56. Two malignant cysts were found among 20 patients who underwent surgical resection during follow-up. Old age was also associated with the presence of a premalignant or malignant cyst (P<0.01). Although the majority of incidental pancreatic cysts show an indolent behavior, long-term, regular follow-up studies should be considered for all pancreatic cysts, especially in the elderly.