During the years 1968-1988 270 patients with tumors and mediastinal cysts were treated surgically. In 48 (17.8%) cysts were found (26 males, 22 females, age ranged 10-63 years, mean 40.1 years). In 24 pericardial cysts were found. In 24 the cysts derived from the forgut. 23 subjects (47.9%) were symptomless. In all the cysts were removed. Mortality was not seen. 47 patients are included in long-term observation.