Twenty patients with hepatic malignancy were treated with transcatheter arterial embolization (TAE) under examination by intra-arterial digital subtraction angiography (IA-DSA) and conventional angiography (CA). Comparison of these two angiographies revealed that the time required for confirmation of the embolized portion of the artery was about four-and-a-half times shorter with IA-DSA than CA. Moreover, IA-DSA revealed the obstructed portion more readily and accurately than CA. In particular, confirmation could not be made by CA in 35% of cases because of residual Gelform sponge containing contrast medium in the artery. The visualization of residual tumor stain after TAE was 40% better on IA-DSA than CA, because of residual Gelform sponge containing contrast medium and overlapping shadow with calcified costal cartilage, excretory pyelography, and original tumor stain. However, CA was better than IA-DSA in visualizing accidental obstruction of nonobjective arteries such as the cystic artery because of the poor spatial resolution and misregistration artifacts of IA-DSA. CA was better than IA-DSA in visualizing surrounding nonembolized hepatic parenchyma because of the misregistration artifacts of IA-DSA. For effective TAE without severe complication, we concluded that TAE for HCC should be performed under a combination of IA-DSA and CA.