The purpose of this experimental study was to compare the effects of using static visuals versus computer-generated animation to enhance learners' comprehension and retention of a content-based lesson in a computer-based learning environment for learning English as a foreign language (EFL). Fifty-eight students from two EFL reading sections were randomly assigned to one of two computer-based instructional modules developed for this study. Once having interacted with their respective instructional materials, students then took four criterion tests both immediately afterward and again four weeks later. The results showed that the animation group outperformed the static visuals group in only one of the four tests, consistent for both the immediate and delayed posttests, indicating comparatively less positive effect from animation use in an EFL context. (Contains 2 figures and 2 tables.)