Immunohistochemical reactions for neurofilaments (NF), peripherin (PRP), synaptophysin (SP), and tyrosine hydroxylase, combined with Nissl staining with toluidine blue, were used to study thick sections passing through all segments of the pancreas of adult white rats (n = 7). The topographies and distribution densities of processes were determined in different parts of the pancreas. The greatest density of processes was seen in the body of the gland. Abundant innervation of the organ by nerve plexuses was found: a large-looped plexus consisting of nerve trunks and bundles of myelinated and unmyelinated nerve fibers staining for NF, a second consisting of fine postganglionic bundles of axons and microganglia, staining for PRP, and a third, detected with reactions for SP, which was the main terminal plexus and consisted of axons with varicose thickenings with en passant synapses. The interactions between SP-positive terminals (distant en passant synapses) and blood vessels, endocrine (islet), and exocrine cells and the output ducts of pancreatic lobules are described in detail; the structural characteristics of the parasympathetic ganglia, their neurons, and the pericellular synaptic apparatus are presented; questions regarding the innervation and nature of the endocrine cells of islets are discussed. Attention is drawn to the fact that neurons were not detected in the islets of the rat pancreas in any case.