This paper presents a novel approach that avoids unnecessary frame buffer accesses by exploring reusable frame buffer data for MPEG-4 simple profile video decoders. In an MPEG decoder, each decoded macroblock is stored in the frame buffer for future reference and video display. If a newly decoded macroblock overwrites the predecessor that is exactly the same, then the old data stored in the frame buffer are reusable. Frame buffer accesses of this kind become unnecessary. We propose a design that greatly reduces the number of such unnecessary memory accesses through the detection and management of the reusable data in the frame buffers. The experimental results show that the proposed scheme achieves as much as 53% (28% on the average) saving in frame buffer accesses, without any sacrifice of the image quality and with only a negligible hardware overhead.