Lysosomal enzymes, cathepsin B and D, have been studied in their possible relationship to the ability of malignant cells to invade and metastasize. In the current investigation, these cathepsins were detected immunohistochemically using avidin-biotin-peroxidase complex method in the pancreatic cancer cells of 21 patients. The positive rate of identification of cathepsin B and D was 43% and 81%, respectively. Cathepsin D stained more strongly than cathepsin B and the plasma membrane stained quite strongly in two instances. A correlation between the presence of cathepsin B or D in cancer cells and the degree of metastasis to lymph nodes, liver, or lung was not recognized.