According to the distribution of the dermal melanocytes, Ota's nevus was classified into 5 types: superficial (type S), superficial dominant (type SD), diffuse (type Di), deep dominant (type DD), and deep (type De). The histological types were, as expected, relatively well-correlated with the color of the nevus: the most brownish lesions represented type S or type SD, while the most bluish lesions showed types Di, DD or De. Furthermore these types were strongly correlated with the location of the nevus: types S and SD were more frequent on cheeks, whereas types Di, DD and De more frequently occurred on eyelid, temple and forehead. When combining both colorations and locations of the nevus, our classification appeared much more significant. Our new histological classification of Ota's nevus may be very useful in making a therapeutic prognosis of the disease.