The evaluation of mural invasion (T) in primary urinary bladder carcinoma is important in the planning of an appropriate surgical or radiochemotherapeutic strategy. Previous investigators using computed tomography (CT) have evaluated the bladder filled with urine, urine opacified with iodinated contrast material, or air insufflation. The purpose of this trial was to establish which of these three techniques was the most accurate by comparing data obtained in postoperative staging (pT). Sixty-five patients with primary bladder cancer were enrolled, all of whom were studied by spiral CT with these three techniques. Patients were assigned to four stage groups: Ta-T1, T2-T3a, T3b, and T4. The results demonstrated total accuracies of 95% for the air-insufflated bladder, 90.5% for opacified urine, and 87% for noncontrast studies. In conclusion, the air-insufflated bladder is the more accurate technique in the evaluation of the T parameter in primary bladder cancer, especially in the first and third stage groups.