The glycoconjugates of regenerative acinar cells, acinic cell carcinomas, islet cell tumors, and normal canine and feline pancreas were studied. The authors used biotinylated lectins as probes and avidin-biotin-peroxidase complex as visualant to identify and to compare the distribution of carbohydrate residues on paraffin sections from 74 cases. The findings demonstrate a difference in the staining pattern between normal acinar, islet, and ductal cells in each species and small differences in the staining pattern between the species. It is shown that in nodules of regenerative acinar cells and acinic cell carcinomas there is an increased staining intensity with Concanavalia ensiformis agglutinin, Ricinus communis agglutinin-I, and wheat germ agglutinin. The pattern of lectin staining in regenerative cells and malignant acinar cells reflects the degree of cellular differentiation. Intensive apical staining characterizes a higher degree of differentiation, while dispersed staining is a major feature of poor differentiation. These findings suggest that malignant transformation of pancreatic acinar cells is associated with enhanced expression of glycoconjugates, which resembles that seen in a normal immature acinar cells.