Basic fibroblast growth factor (bFGF) has well-established angiogenic and ulcer healing actions. bFGF has also been found to induce neural regeneration in the central nervous system. Thus, the present study was undertaken to clarify the effect of basic fibroblast growth factor on the regeneration of autonomic nerves in the granulation tissues following the induction of experimental gastric ulcer induced by acetic acid in rats. Rats were divided into control, acetic acid alone, and acetic acid plus acid-stable human recombinant basic fibroblast growth factor (CS23, 1 microgram/100 g body wt., every 12 hr for three days, or one or two weeks, through oral gastric intubation) groups. As a result, few autonomic nerves were recognized surrounding the newly formed arterioles and venules in the acetic acid alone group. In the CS23-treated group, the cholinergic, calcitonin gene-related peptide and vasoactive intestinal peptide-immunoreactive nerves were clearly recognized near the microvessels, but few adrenergic nerves were seen even after CS23 treatment. From these observations, basic fibroblast growth factor was suggested to promote the reinnervation of the newly formed microvessels.