Gelatin sponge particles were rendered radiopaque by soaking them in small amounts of iodized oil (LP-GS). They were evaluated for their usefulness in transarterial embolization (TAE). The LP-GS particles were well visualized fluoroscopically during TAE. The duration of the opacity of LP-GS exceeded 24 hours both in vitro and in vivo. LP-GS are useful, and are an easily obtainable, radiopaque, embolic material.