Natural dyes have attracted the worldwide attention because of its environmental advantage over synthetic dyes. However, most of natural dyes are expensive for mass production, strongly season and source dependent, and hard to store. In this study, coffee waste were used as natural dye to create beautiful colors. Coffee waste is inexpensive and easy to store, and provides a comparatively regular quality regardless of seasonand source. The effects of mordant agent concentration and mordanting temperature on dyeing efficiency of silk fabrics were investigated. Coffee extract dyed silk showed brilliant colors, and the colors were different with the kind of mordants. Cu, Sn, and Al mordanted silks showed golden yellow with subtle change of hue and value, while Fe mordanted silk showed a brownish green color. The increase in mordant concentration did not always increase the dyeability, and 0.5% o.w.f. mordant concentration was enough to get a satifactory result. Mordanting temperature also had little effect on the dyeability in case of Al, Cu, and Sn mordanted fabrics. Only Fe mordanted fabrics showed a better dyeability in the increase in mordating temperature. Coffee extract dyeing is an effective way using waste as resource and can create brilliant colors with minimal amount of mordant and under mild mordanting condition.