This study was performed to confirm the high sensitivity of CT during arterial portography (CTAP) versus US and dynamic CT in the diagnosis of liver metastases from colorectal cancer. Ninety patients with 108 colorectal cancers underwent US, dynamic CT and CTAP to investigate the presence of liver metastases. US depicted 39 metastases in 26 patients, dynamic CT 46 metastases in 29 patients and CTAP 54 lesions in 34 patients. CTAP detected 8 metastases missed at dynamic CT; 4 of them were < 1 cm in diameter, 3 ranged 1-2 cm and one metastasis > 2 cm in diameter. After preoperative investigations only 7 patients were considered for hepatic resection. At surgery, palpation and intraoperative US of the liver detected two more metastases in the same patients. Our experience, in agreement with recent studies, confirms CTAP as the most sensitive preoperative method in detecting liver metastases and its superiority to be most apparent in lesions < 1 cm in diameter. Therefore, we consider CTAP an essential imaging technique for planning the correct treatment of liver metastases.