Intrarectal ultrasonography is a new imaging method used in the preoperative staging of rectal cancer. Twenty five patients with proven rectal cancer were submitted to preoperative intrarectal ultrasonography; 24 were resected. Real time scanner with a linear probe of 5 MHz was employed. Five sonographic structures corresponding to the five histological layers were evidenced. Ultrasound T staging was compared to pathology, using UICC classification. In all but two cases pathology corresponded to ultrasound T staging (accuracy 92%). Perirectal nodal involvement was also investigated. It is concluded that intrarectal ultrasonography will play a definite role in the preoperative staging as well as in programming treatment of rectal carcinoma.