The present study explored the effects of figure/ground color combinations on legibility of small icons. This experiment used a 2 (icon size) x 3 (icon hue) x 3 (icon saturation) x 3 (background hue) x 3 (background saturation) x2 (luminance contrast) factorial design. Legibility was investigated by response time of subicons with different factors t hat affect discrimination. 11 undergraduate students from the National Formosa University in Taiwan were recruited to participate in the experiment. Their mean age was 21.8 yr. (SD=3.3). Analysis also showed that Icon Size x Luminance Contrast, Background Hue x Luminance Contrast, and Background Saturation x Luminance Contrast significantly affected response time. The results suggested that the higher Luminance Contrast could promote icon legibility but not the icon chromaticity or background chromaticity.