Color observation is essential to diagnose oral mucosal lesions. In order to measure and record the color of the oral mucosa more objectively, colorimeters were evaluated. The noncontact-type colorimeter showed considered values comparable with those of visual color matching and was reliable. The color distribution of the normal oral mucosa was from 5.0R to 4.1YR in hue, 3.5 to 6.0 in value, and 3.7 to 6.7 in chroma. The color distribution of leukoplakia was from 2.6RP to 3.4YR in hue, 3.7 to 7.0 in value, and 0.3 to 8.3 in chroma and the ranges thereof were considerably broader than those of normal mucosa and other mucosal lesions. The higher chroma of leukoplakia was, the severer epithelial dysplasia was. The color distribution of oral cancer was from 3.0R to 8.2YR in hue, 2.7 to 6.4 in value, and 3.0 to 7.8 in chroma. The ranges of color distribution was broader than those of normal mucosa and narrower than those of leukoplakia. The color distribution of lichen planus was from 1.7R to 8.9R in hue, 3.5 to 6.3 in value, and 3.6 to 8.5 in chroma. The chroma of erythema is the highest of all mucosal lesions. Some oral mucosal lesions are suggested to have characteristic colors.