Fifty consecutive patients presenting with fecal incontinence were evaluated prospectively with anorectal manometry, defecography, and other tests of anorectal function to assess the clinical utility of defecography in fecal incontinence. Leakage of contrast at rest and failure to narrow the anorectal angle with pelvic squeezing were specific but not sensitive predictors of decreased sphincter pressures as determined by manometry. Thus, after manometry, defecography provided no additional information regarding sphincter strength. Retention of contrast in large rectoceles or incomplete rectal evacuation at defecography had excellent correlation with the presence of clinical symptoms of outlet obstruction constipation (present concurrently with incontinence) and indicated an etiology of outlet obstruction symptoms. Defecography may provide useful information in incontinent patients with outlet obstruction constipation symptoms but has little additive value to anorectal manometry in incontinent patients without such symptoms.