Endoanal ultrasound was used in the investigation of 26 patients with faecal incontinence. In each case images of the anal sphincter were taken at rest and during contraction or squeezing (dynamic). Better definition of the normal anal sphincter or anal sphincter defects was obtained in 16 (62%) of the patients with imaging during contraction. In eight of the 13 patients with a sphincter defect there was better definition of the defect and increased separation of the ends of the sphincter during contraction. Imaging during contraction improves diagnostic accuracy and is a useful adjunct with endoanal ultrasound.