We have measured serum immunoreactive pancreatic elastase 1 concentrations in 90 patients with pancreatic cancer in order to determine its usefulness in the diagnosis of this tumor. Abnormal elastase 1 concentrations were found in only 58 (64.4%) of the 90 patients. Fifty (55.5%) had abnormally high values, and eight (8.9%) had abnormally low values. No significant differences in elastase 1 levels were observed between patients with resectable cancer (n = 15) and those with unresectable cancer (n = 75). Moreover, no significant differences were found between elastase 1 concentrations of patients with pancreatic cancer and those of 71 patients with chronic pancreatitis. We conclude that serum elastase 1 measurement does not represent a significant advance in the diagnosis, whether early or late, of pancreatic cancer.