To evaluate the results and clinical impact of defecography in patients with anorectal diseases, 304 defecographic examinations from 304 patients were reviewed. The defecographic results were screened for the anorectal angle and perineal descent at rest, squeezing and during straining. Changes of rectal configuration and canal width during straining were reviewed. 304 patients had defecation problems such as terminal constipation, defecation defficulty, blood or mucus discharge, tenesmus, obstruction sensation etc. They were performed anorectal physical examination and anal manometry etc., and were later treated by operation and conservative management. Normal anorectal angle were measured to be 101°, 91°, 131°at rest, during squeezing and straining respectively. In the spastic pelvic floor syndrome, increase of anorectal angle less than 10 ° from rest to straining was observed. Incontinent patients had a larger anorectal angle (mean: 128°) at rest. 7.8cm of perineal descent was found in descending perineal syndrome in comparison to 4.0cm in normal. Normal anal canal width was measured 1.4cm only during straining but identified in incontinent patients at rest (mean:1.2cm). Abnormal rectal configuration was found in 254 defecographic examinations: rectoceles were observed in 235 cases and were associated with rectal prolapse in 115 cases, and rectal prolapses were found in 134 cases. In conclusion, the anorectal angle was valuable in evaluation of spastic pelvic floor syndrome and fecal incontinence. Degree of perineal descent was abnormally increased in descending perineal syndrome. In the cases of the rectoceles and rectal prolapses, defecography is helpful in preoperative evaluation of rectal wall change and postoperative follow up.