A comparison of transrectal ultrasound (TRUS) and computed tomography (CT) for staging of rectal carcinoma was performed. Thirty-two patients were examined by TRUS and 30 by CT. The results of these preoperative examinations were compared with postoperative histopathological findings. TRUS had an accuracy of 81% and it predicted perirectal tumor growth with a sensitivity of 90% and a specificity of 67%, whereas the corresponding figures for CT were 52%, 67%, and 27%. These findings indicate that TRUS is more efficient than CT in staging local tumor growth in rectal cancer. Neither technique, however, can reliably identify lymph node metastases, since no correlation was found between lymph node size as observed on CT and TRUS and tumor involvement as evaluated histopathologically.