The serum values of tissue polypeptide antigen (TPA) were measured in a prospective series of 100 patients with jaundice, 54 patients with suspicion of chronic pancreatitis or a pancreatic tumour, and 19 patients with unjaundiced cholestasis to assess its value in diagnosing pancreatic cancer. There were altogether 25 patients with a cancer of the pancreas including 2 patients with a cancer of the papilla of Vater. The highest serum TPA values were noticed in patients with pancreatic cancer, but raised values were also seen in patients with malignant or benign liver diseases, and with cholangiocarcinoma. The sensitivity of TPA was 52% with a specificity of 85% and an efficiency of 80%. In comparison to CEA, CA 50 and CA 242, TPA showed lower sensitivity but higher specificity. When TPA was combined with the other markers, the specificity and efficiency improved clearly in all combinations, being highest in that of TPA and CA 242 (specificity 94.5%, efficiency 87.2%). The results suggest that the TPA test has a useful complementary role in the clinical use of the current serum tumour markers in the diagnosis of pancreatic cancer.