Defecography is performed by fluoroscopic study of the pelvic floor and ano-rectal region during defecation after injection of plasty barium into the rectum. This radiological examination provides imaging of anatomical changes of ano-rectal region and pelvic floor. It also provides clues for diagnosis of some pathology related to defecation and guides for clinical management. From Jan. 1988 till June 1988, sixteen cases with problems of defecation was refcrred to our department for defecography, two with internal intussusception of the rectum, five with spastic pelvic floor syndrome, four with rectal prolapse and two with rectocele. The clinical manifestations and radiologic pictures of these disorders were presented. The pathogenesis and the literatures were brief reviewed.