The electrical conductivity of resins can be increased by adding electrically conductive carbon fillers. A significant amount of work has been conducted varying the amount of single conductive fillers in a composite material. Limited work has been conducted concerning the effect of combinations of different conductive fillers. In this study, three different carbon fillers were used in nylon 6,6: carbon black, synthetic graphite particles, and a surface treated polyacrylonitrile (PAN) based carbon fiber. The goal of this project was to determine the effect of each filler and combinations of different fillers on the electrical conductivity of conductive resins. A 2(3) factorial design was analyzed to determine the effects of the three different carbon fillers in nylon 6,6. The results showed that carbon fiber caused the largest increase in composite electrical conductivity and that all the combinations of different fillers do have a statistically significant effect on composite electrical conductivity. (C) 2004 Wiley Periodicals, Inc.