SummaryAnatomy:The profound perineal loge is described. That portion of the rectum which occupies the loge is established as an entity which the author designates as the “perineal segment of the rectum.”Pathology:Extramural extension of cancer is studied according to precise description of the anatomy of the region. Emphasis is placed on “local invasion of the loge.” Metastasis may be expected in the five areas of the rectum described, but of most importance is the ventrolateral area of the pelvis.Surgery:The operation consists of total amputation by the perineoabdominal approach with removal of the profound perineal loge and the areas of regional spread.