The tumor-detecting capacity and clinical usefulness of superparamagnetic iron oxide (SPIO) magnetic resonance imaging (MRI) were examined in patients with hepatocellular carcinoma. The tumor detection rate of SPIO-MRI (64.5%) was comparable to those of dynamic computed tomography (CT) and plain MRI, but lower than that for Gd dynamic MRI (93.5%; P < 0.01%). A combination of Gd dynamic MRI and SPIO-MRI improved the detection rate; further, the tumor stage with respect to tumor blood-flow pattern was predicted by combining plain MRI with SPIO-MRI. This combination procedure may also be useful for selecting therapeutic strategies.