Ultrasonographic studies in healthy volunteers showed that the external anal sphincter (EAS) and internal anal sphincter (IAS) thicknesses were inversely related at rest. The functional importance of the two sphincters in continence control was demonstrated in the relationship between the sum of the thicknesses of the two sphincters and the anal canal resting pressure. The aims of the present study were to assess the morphometric appearance of the anal sphincters by endosonography in faecally incontinent patients and to contrast this with that of older healthy subjects.