We have investigated the expression of angiogenin (ANG) in pancreatic cancer and the relevance of ANG expression to the progression of pancreatic cancer. In comparison to normal pancreas, increased ANG mRNA expression was observed in 80.0% of the cases of pancreatic cancer by in situ hybridization, and increased ANG protein expression was observed in 86.7% of the cases of pancreatic cancer using Western blot analysis. The mean serum ANG concentration of pancreatic cancer patients (566.6 +/- 191.9 ng/ml) was significantly higher (P < 2.0 x 10(-8)) than that of healthy volunteers (359.0 +/-t 59.9 ng/ml). Increased ANG mRNA expression as well as elevated serum ANG concentration correlated with poor prognosis. These findings suggest that ANG expression is up-regulated in pancreatic cancer patients and that ANG contributes to the aggressiveness of pancreatic cancer.