Pancreatic cystadenoma (CA) are rare tumors. According to the classification described by Compagno and Oertel, microcystic and macrocystic CA are differentiated. The former is a benign tumor with slow growth, but the latter has a malignant potential. According to the literature, these tumors may be differentiated on the basis of US and CT findings in a high percentage of cases. We report a series of 11 cases (5 microcystic CA, 4 mucinous CA, 1 leiomyoblastoma and 1 adrenal cyst) representing all cases of radiologically suspected CA and all cases of histologically proved CA. A correct diagnosis of microcystic CA was possible in 2 out of 5 cases, and in 3 out of 4 cases of mucinous CA. The 2 extra-pancreatic tumors were misinterpreted as mucinous CA. No patient had a false positive diagnosis of microcystic CA. The diagnosis of mucinous CA was made in 7 cases, but only 3 were true positives. There was 1 false negative of mucinous CA. In other cases, laparotomy and resection are mandatory as sonography and CT cannot accurately detect malignancy or differentiate pancreatic CA from adjacent sites tumors.