Purpose The aim of this study was to evaluate the clinical significance of perineal descent (PD) in pelvic outlet obstruction patients diagnosed by using defecography. Methods One hundred thirty-six patients with pelvic outlet obstruction (POO; median age 49 years) had more than one biofeedback session after defecography. Demographic finding, clinical bowel symptoms and anorectal physiological studies were compared for PD at rest and PD with dynamic changes. Results Age (r = 0.33; P < 0.001), rectocele diameter (r = 0.31; P < 0.01), symptoms of incontinence (P < 0.05) and number of vaginal deliveries (r = 0.46; P < 0.001) were correlated with increased fixed PD. However, the female gender (P < 0.005), rectal intussusceptions (P < 0.05), negative non-relaxing puborectalis syndrome (P < 0.00005) and rectocele (P < 0.0005) were correlated with increased dynamic PD. Duration of symptoms, number of bowel movements, history of pelvic surgery and difficult defecation were not related with PD. There was no significant correlation between fixed and dynamic PD and success of biofeedback therapy. Conclusion Age, vaginal delivery and diameter of the rectocele are associated with increased fixed PD. Female gender, rectal intussusceptions and a rectocele are correlated with increased dynamic PD. Biofeedback is an effective option for POO regardless of severity of PD.