Sixteen patients aged 12 to 16 years (mean, 14.9) with corrected low anorectal anomalies, and eight age-matched controls were studied. Eight patients were totally continent, six had staining, and two had fecal soiling. Half the patients had trouble with constipation. The grade of incontinence was related to significantly reduced resting and squeeze pressure in the anal canal. Girls had significantly worse results than boys. The anal sphincter muscle complex was visualized by anal endosonography, and images of the external anal sphincter corresponded to the results of the surface electromyography. In addition, anal endosonography provided a detailed picture of all perianal structures including the internal anal sphincter. Anal endosonography supplements other imaging techniques for assessing the perianal structures in patients who have an accessible anal canal.