The purpose of this study was to evaluate the role of combined CT hepatic angiography (CTHA) and CT during arterial portography (CTAP) in the diagnosis and management of patients with hepatocellular carcinomas (HCC) and liver metastases. Fifty patients with HCC and 19 patients with liver metastases were referred for CTHA and CTAP prior to surgery or interventional therapy. Diagnosis was established by either surgery or clinical observation. Alterations of diagnosis and management resulting from CTHA and CTAP information were recorded. In patients with HCC, diagnosis was altered either by number, location or extent of lesions in 46% of patients and was 78% correct. Alterations of management were performed in 32% of the patients in total, and were correct in all but one. In patients with liver metastases, diagnosis was altered regarding either number, location or extent of lesions in 21% of patients and were 50% correct. Management was not altered after CTHA and CTAP in the patients with liver metastases. We conclude that CTHA and CTAP provide valuable clinical information for patients with HCC and significantly corrected their previous diagnosis and plans of management. CTHA and CTAP should be performed in patients with HCC when either surgical or interventional therapy is the treatment option.