20 percutaneous aspirations, guided by ultrasound, were performed without serious complications in 17 patients with cystic pancreatic lesions. Amylase activities of all 10 pseudocysts were increased with a considerably wide range (3,680–775,000 U/l) and the serum amylase level correlated significantly (p < 0.01) with the enzyme activity of cyst content. The enzyme level of 1 true cyst and 2 cystic malignancies were in the normal range of serum amylase; low amylase activity does not rule out a pancreatic origin of a cystic mass lesion. Bacteriological and cytological studies of aspirated samples revealed 2 (of 2) pancreatic abscesses and 2 (of 3) cystic malignancies. Total regression of an acute pancreatic pseudocyst was achieved following repeated percutaneous antegrade evacuation