In a retrospective study of patients treated between 1974 and 1979 with surgery alone for cancer of the rectum or rectosigmoid, a total of 293 patients were evaluated. All original histopathological specimens were re-examined and classified according to the Dukes' staging system and to the Astler - Coller 's modification of this system. Among the 197 (67%) patients operated upon for local cure, 74 patients developed a microscopically proven local recurrence (38%), and in 43 of them this was the only sign of recurrent cancer. There was no clear correlation, however, to the pathological stage. Possible explanations for this finding will be discussed.