To analyze the sonographic findings of rectal cancer, we reviewed 61 sonograms of patients with proven rectal cancer. The sonographic findings of rectal cancer showed a thickening of the rectal wall, over 6mm and/or a focal mass in the rectal wall. In evleven cases, sonography was the first test to raise the probability of rectal cancer which was subsequently confirmed. Abdominal sonography could beused to detect rectal cancer by recongnizing a thickening and/or a focal mass in the rectal wall.