Biofeedback therapy improves symptoms inpatients with constipation and obstructive defecation.Whether it also improves anorectal function is unclear.Our purpose was to investigate prospectively the effects of biofeedback therapy on subjective andobjective parameters of anorectal function in 25consecutive patients with obstructive defecation.Biofeedback therapy consisted of pelvic floor relaxationexercises (phase I) and neuromuscular conditioning ofrectal sensation and rectoanal coordination, with asolid state manometry system and simulated defecationmaneuvers (phase II). The number of sessions wascustomized for each patient. Clinical improvement wasassessed from the changes in anorectal manometry,balloon (50 cc) expulsion test, and the symptom andstool diaries. The number of therapy sessions varied[mean (range) = 6 (2-10)]. After therapy, whenstraining as if to defecate, the percentage analrelaxation, intrarectal pressure, and defecation indexincreased (P < 0.001). The balloon expulsion time,laxative consumption, and straining effort decreased (P< 0.001). Before therapy, 16/25 (64%) patients hadimpaired rectal sensation, and after therapy thisimproved (P < 0.001). After therapy, 15/25 (60%) patients reported 75% satisfaction with bowelhabit and 8/25 (32%) reported ≥50% satisfaction (P< 0.001); 15/16 (94%) patients discontinued digitaldisimpaction. Biofeedback therapy not only improves subjective but also objective parameters ofanorectal function in at least 76% of patients byrectifying the underlying pathophysiologicdisturbance(s). Sensory conditioning and customizing thenumber of sessions may offer additionalbenefits.