Anorectal function was evaluated in 11 patients with voiding dysfunction due to multiple sclerosis. In six patients with constipation, three also had symptoms of obstructed defecation and one patient was incontinent due to stercoral diarrhea. One patient was only fecal incontinent and one patient had obstructed defecation as the only symptom. Three patients had no anorectal symptoms. Anal manometry in the women compared with a control group revealed significant lower anal resting and squeeze pressures, although no significant difference of rectal sensation to distention with air was found. Pudendal nerve terminal latencies were obtained in seven patients and were all normal. In four patients latency could not be demonstrated due to poor contraction of the sphincter on stimulation of the pudendal nerve. Two of these patients were incontinent and two had both constipation and obstructed defecation. It is concluded that patients with voiding symptoms due to multiple sclerosis often reveal anorectal symptoms or motility disorders. Although anal sphincter function is reduced, fecal incontinence is not prevalent in this group. The reason for this lies probably in the fact that many of the patients are constipated, thus securing fecal continence.