The present study explored the effects of figure/ground color combinations on legibility of small icons. This experiment used a 2 (icon size) × 3 (icon hue) × 3 (icon saturation) × 3 (background hue) × 3 (background saturation) ×2 (luminance contrast) factorial design. Legibility was investigated by response time of subjects to icons with different factors that 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 × Luminance Contrast, Background Hue × Luminance Contrast, and Background Saturation × 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.