The color stability of current prosthetic composites is unknown, even though the quality of composite materials has been improving. This study examined the intrinsic color stability of various current prosthetic resins (ceramic-polymers) after an accelerated aging process and the extrinsic color stability after immersion in a coffee solution. By comparing the amount of discoloration after aging with that without aging, the effect of the accelerated aging process on external discoloration could be evaluated. Three current prosthetic composites (Artglass, Targis, Sculpture), one light polymerized direct composite (Z100) and one dental porcelain control (Ceramco) were assessed. The color changes (${Delta}$E) of all the specimens were determined using the CIE $L^{*}a^{*}b^{*}$ color order system with a reflected spectrophotometer. The results were as follows: 1. The prosthetic composite materials subjected to the accelerated aging test showed no significant difference in color changes (p >.05). 2. In the coffee solution immersion test after the aging process, the color changes of the Targis and Artglass groups were not different from that of the Z100 group, which showed the highest color change. 3. In the immersion only test, a significantly high color change was observed in the sculpture glazing group. 4. The aging process influenced on the color changes more in the Targis, Artglass and Z100 groups than in the Sculpture and Ceramco groups.