Objective methods of measuring skin color are needed to evaluate pigmentary lesions quantitatively. We have developed a new method of measuring skin color using a plastic bar system called the Skin Tone Color Scale based on Munsell's color space system. We have also evaluated the effectiveness of various therapies using this measurement system. Our system was designed to measure skin color in normal skin, pigmentary lesions of solar lentigo, chloasma and ephelides, and postinflammatory pigmentation. Moreover, effectiveness of various therapies for these pigmentary lesions was evaluated. The evaluations made with this system were closely related to physician assessment. This method may be useful in measuring of skin color and evaluating the effectiveness of therapies for pigmentary diseases.