This work is devoted to the study of adrenergic terminal structures in the mesentery of mammals (cat, dog). The investigation was performed with the Falck-Hillarp method of catecholamine fluorescence microscopy on total stretch mesentery preparations. The investigation showed that richly developed perivascular plexus constitute the basis of the adrenergic innervation system of the mesentery. In numerous points of these plexuses, single adrenergic fibers or polyaxonal structures are observed to issue into nonvascular areas of the mesentery where after repeated dichotomic division they pass into the preterminal and terminal parts. Being constructed on the principle of extended or restrained arborizations, these innervating structures have a morphological similarity with free sensory nerve endings. In this connection, the question of the possible existence of the sensory (afferent) links in the catecholamine-containing vegetative nerve plexuses is discussed.