To analyze the secretory mechanism of immunoglobulins into pancreatic secretion, pancreatic juice IgA was measured by single radial immunodiffusion and characterized immunochemically, and immunoglobulins, J chain and secretory component (SC) were localized immunocytochemically in pancreatic tissues by the peroxidase-labeled antibody method. The concentration of IgA was 0.0225 mg/ml with a range of 0.010 to 0.049. IgA associated with SC was demonstrated immunochemically in three cases. IgA, SC and J chain were demonstrated immunocytochemically in the pancreatic duct epithelium with the features characteristic of endocytic, SC-mediated transfer of IgA. The results of the present study suggested that transfer of IgA linked by J chain and SC across ductal epithelial cells, but not acinar cells occurred in human pancreas.