Forty fine needle aspiration (FNA) biopsies of the pancreas were performed on 37 patients with a radiologic suspicion of malignancy; 32 aspirations were guided by ultrasound, 2 were guided by CT, and 6 were obtained intraoperatively. A pathologist read a rapid-stained smear of the initial aspirate as the procedure was performed and triaged specimens for routine cytologic, cell block and ultrastructural study in solid lesions plus carcinoembryonic antigen (CEA) assay and amylase study in cystic lesions. Purulent material was studied by gram staining and culture. The overall sensitivity in the series was 81%, with a specificity of 100%. No complications were noted. Ultrastructural examination improved the diagnostic accuracy in two cases. Assays for CEA and amylase in "cyst fluids" differentiated true cysts and cystadenocarcinoma from pseudocysts. Maximum utilization of the material aspirated was useful in diagnosing the etiology of solid and cystic pancreatic masses.