A biotinylated hyaluronate (HA)-binding protein isolated from bovine cartilage was used to analyze the distribution of HA in nude mouse xenografts derived from human pancreatic adenocarcinoma cell lines as well as in primary human pancreatic adenocarcinomas. The most reproducible results for the localisation of HA were obtained using cryostat sections. When the biotinylated HA-binding protein was applied to histological sections of nude mouse xenografts, the specific staining found could be inhibited by preincubating the HA-binding protein with an excess of HA or by hyaluronidase treatment of the tissue before staining. The highest HA concentration was found at the tumor boundaries, while in the central part of the tumor staining was slight or absent. In cryostat sections of primary tumors HA was found predominantly in the connective tissue immediately around tumor cells or at the border between the tumor and normal pancreatic tissue.