The CT findings of thirty-three patients with proven colon cancer were analysed. The results were as follows: 1. The accuracy for detecting pericolic fat invasion on CT was 81%. 2. The accuracy for detecting lymph node involvement on CT was 67%. 3. The overall accuracy for staging of colon cancer on CT was 64%(67% for stage A, 30% for stage B, 60% for stage C, 100% for stage D). 4. The overall detection rate of mass on CT was 80%(89% for rectum, 100% for rectosigmoid colon and sigmoid colon, 30% for ascending and transverse colon). 5. The CT is useful, nonivasive technique for assessing extension and staging of colon cancer.