The collagen content in human pancreatic cancer tissue, tissue of tumor-associated chronic pancreatitis (TACP), and normal pancreatic tissue was determined in 14 patients with pancreatic cancer by measuring the amount of 4-hydroxyproline. Four patients with alcoholic chronic pancreatitis (AlCP) were also analyzed. The mean collagen content in both pancreatic cancer tissue and TACP tissue was approximately threefold higher than in normal pancreatic tissue. Cyanogen bromide peptides of type I, III, and V collagens from invasive ductal carcinomatous tissue of the pancreas and from TACP tissue of eight patients were analyzed sequentially using high-performance liquid chromatography with ion-exchange and gel-permeation columns. No difference in the proportion of type I, III, and V collagens was detected between pancreatic cancer tissue and TACP tissue. The mean collagen content in AlCP tissue was significantly lower than that in TACP tissue, but no difference in the proportion of type I, III, and V collagens was detected between these two tissues. These results indicate a similar quantity and distribution pattern of fibrillar collagen in human pancreatic cancer and TACP.