To assess whether triphasic spiral CT enables characterization of a wide range of focal liver lesions. One hundred five patients with suspected focal liver disease underwent triphasic liver CT. After injection of contrast material, the liver was scanned in arterial (scanning delay, 22-27 seconds), portal (scanning delay, 49-73 seconds), and equilibrium (scanning delay, 8-10 minutes) phases. Enhancement of each lesion in each phase was evaluated, and the lesions were tabulated according to one of 11 enhancement patterns. In 94 patients, 375 liver lesions were detected. The nature of the lesion was confirmed in 326 lesions (87%). Six of 11 enhancement patterns were always due to benign disease and caused by areas with hyper- or hypoperfusion, hemangiomas, cysts, focal nodular hyperplasias, or benign but nonspecified lesions. Two of 11 patterns were always due to malignant disease, and one pattern was due to malignant disease in 38 (97%) of 39 patients with known malignancy elsewhere or with chronic liver disease. The other two patterns were seen in metastases and partly fibrosed hemangiomas. Triphasic liver CT enables characterization of a wide range of focal liver lesions, including the benign liver lesions that occur most frequently.