An immunohistochemical study of biopsy samples obtained from 7 patients with chronic pancreatitis were performed using reactions to neurofilaments (NF), synaptophysin (Syn), chromogranin (CgA), myelin basic protein (MBP), and protein gene product 9.5 (PGP 9.5). Results obtained demonstrated high selectivity for revealing the endocrine cells of the islets of Langerhans for three markers: Syn, CgA, and PGP 9.5. In all the cases under investigation, the head of pancreas exhibits significant dystrophic and degenerative changes in neurons of intramural ganglia, nervous stems and bundles, demyelination of nervous fibers, destructive changes in epi-, peri-, and endoneurial sheaths, decrease or total loss of Syn-immunopositive efferent terminals around blood vessels and pancreatic ducts, denervation of glandular tissue of the exocrine and endocrine parts. Besides impairment of innervation, dystrophic changes and reorganization of the islets of Langerhans accompanied by migration and dedifferentiation of various kinds of endocrinocytes were found. In some cases, reaction to PGP 9.5 revealed an increased number of immunopositive nervous bundles, nervous fibers and their terminal branches in the hypertrophic connective tissue, around vessels, and inside or around inflammation infiltrates. It is suggested that PGP 9.5-immunopositive fibers are (nociceptive) afferent receptor apparatuses perceiving pain. The found inflammation infiltrates with a lot of plasmatic cells selectively clustered around the nervous ganglia, nervous trunks and bundles as well as disintegration of myelin sheaths revealed using MBP reaction in pancreatic nerves suggest possible development of autoimmune processes.