Before 1978, where cystic tumors of the pancreas were concerned, pathologists only differentiated between cystic adenomas and cystadenocarcinomas. Recently, however, further tumor entities have been introduced. We now differentiate between the generally benign serous cystic adenoma, the potentially malignant mucinous cystadenoma, the possibly malignant papillary cystic tumor, and the always malignant mucinous cystadenocarcinoma. Other rare tumors include the solid cystic acinous-cell tumor, the cystic islet tumor, and mucinous ductal hyperplasia. Because of their slow growth and primary displacement nature, all of these tumors can usually be detected only after they have attained considerable size. Computed tomography (CT), sonography and endoscopic retrograde cholangiopancreatography (ERCP) have an established role in diagnosis. With these methods, as a rule, it is possible to identify pseudocysts; however, differentiation between the individual tumor types is almost impossible. In our study from 1979 to 1990, we observed ten cases of serous cystic adenomas, nine cystadenocarcinomas, and four malignant papillary-cystic tumors. Of these, nine of the ten serous cystic adenomas, four of the five mucinous cystadenomas, all four papillary-cystic tumors, and five of the nine cystadenocarcinomas were curatively resected. All patients with curatively resected adenomas and one patient with an R1-resected cystic adenoma remained free of recurrence throughout the follow-up period. One 86-year-old female patient in whom a serous cystic adenoma was histologically determined still has no symptoms 8 years after diagnosis despite slow tumor progression. Two of the five patients in whom a cystadenocarcinoma was curatively resected died postoperatively; a third patient died of tumor recurrence 4 months following resection.(ABSTRACT TRUNCATED AT 250 WORDS)