Intraoperative fine needle aspiration cytology of pancreatic lesions. The aim of the present study was to demonstrate the practicality of intraoperative fine needle aspiration (FNA) cytology of pancreatic lesions in 43 patients. The indication for performing this procedure was to determine the nature of pancreatic masses. Conclusive cytologic diagnoses were reached in 41 patients who represent the present study. On the basis of histologic findings in 30 cases (73.2%) and on clinical findings in 11 cases (26.8%), a final diagnosis of malignant pancreatic disease (MPD) was established in 31 and of benign pancreatic disease (BPD) in 10 patients. Among the 31 cases with MPD, the cytologic diagnosis was correct in 30 patients and falsely negative in one patient. Among 10 patients with BPD, all the cytologic finding were reported as benign. The sensitivity and specificity and positive and negative predictive values for cytologic findings were 96.8%, 100%, 100%, and 90.9%, respectively. The diagnostic accuracy of FNA cytology was 97.6%. No complications followed the procedure. We conclude that intraoperative FNA cytology of pancreatic lesions is a simple, safe, highly sensitive, and specific tool in differentiating benign from malignant pancreatic lesions. This procedure should be carried out in any patient with pancreatic mass incidentally found at laparotomy or in a patient undergoing surgery because of suspected nonmetastasizing MPD in whom repeated imaging guided FNA failed to demonstrate malignancy. 