We have studied the pelvic floor musculature and its innervation in 14 of 24 (58 per cent) multiparous women who had been recruited into a study of the effect of childbirth on the pelvic floor as part of a prospective investigation that began in 1983. These 24 women had all delivered by the vaginal route without forceps assistance. Five of the 14 had developed clinical symptoms of stress incontinence 5 years later; two of them had had a further uncomplicated vaginal delivery during this time. There was manometric and neurophysiological evidence of weakness because of partial denervation of the pelvic floor striated sphincter musculature, with pudendal neuropathy, which was more marked in those women with incontinence. These findings provide direct evidence for the hypothesis that pudendal neuropathy due to vaginal delivery persists and may worsen with time.