The aim of this study was to evaluate the preoperative staging of rectal carcinoma by intrarectal ultrasonography using linear probe or curved array transducer. Between October 1991 and July 1993, preoperative staging with endoscopic ultrasound was performed in 45 patients with rectal carcinoma. Twenty-four received preoperative radiation therapy. For carcinoma of the middle and the lower part of rectum, the distance between the inferior pole of the tumour and the levator ani muscle was systematically measured. The ultrasound results were compared with histological and surgical findings. The staging was accurately predicted in 82.2% of cases. The depth of cancer invasion was correct in 93.3% (95.2% when preoperative radiation therapy was not applied and 79.1% after radiation therapy). Presence or absence of lymph nodes metastasis was correctly determined in 84.4% (90.5% when preoperative radiation therapy was not applied and 79.1% after radiation therapy). The distance between the inferior pole of the tumour and the levator ani muscle was correctly determined in 29/31 carcinoma of the middle and the lower part of rectum. While the linear and sectorial technique is more difficult when the tumour was circular, the staging of the lower part of rectum carcinoma and anal canal was easier.