This study presents the case of a patient with neurofibromatosis and megacolon. A diffuse, but patchy abnormality of neural tissue was present throughout the colon, especially in the myenteric plexus, but also in the submucosal plexus, smooth muscles, and lamina propria. This consisted of (a) a marked decrease in the number of argyrophilic neurons within the myenteric plexus, enlargement and deformity of those neurons present, and a marked increase of nerve fibers and nerve tract size in the myenteric plexus; (b) a proliferation of neurons and nerve fibers within the smooth muscle and submucosa; and (c) a proliferation of nerve fibers within focal areas of the lamina propria. The relationship of this case to previously reported cases of neuronal intestinal dysplasia and plexiform neurofibromatosis is discussed. Surgical treatment may be necessary and the surgical options are reviewed.