The authors have employed a real-time fluoroscopic computerized equipment during defecography. Digitalized images were acquired at a rate of three frames/s and then processed and became immediately available. Digital defecography was employed in 67 patients with various anorectal diseases--i.e., rectocele, descending perineum, rectal prolapse, non-relaxing puborectalis syndrome and fecal incontinence. We found time-interval difference (TID) technique especially useful for it allowed different functional phases of defecation to be depicted on a single subtracted image and an evaluation of the movements of anorectal region. The high contrast resolution of the computerized equipment demonstrated even minimal contrast medium leaks in fecal incontinence. The examination is easy and rapid to perform with a low radiation dose to the patients.