Abstract: A method and apparatus for non-invasively measuring skin structure. Infrared radiation over an area of skin under investigation is measured to give an indication of the variation in papillary dermis thickness over said area, and the skin color coordinates at a plurality of locations over the same area of skin is also measured. The data obtained is used to calculate corrected skin color coordinates over the area corresponding to a predetermined papillary dermis thickness. The corrected skin color coordinates so obtained are compared with a reference color coordinate range for healthy skin of the same predetermined papillary dermis thickness. At an abnormal region, where the corrected skin color coordinates lie outside the reference color coordinate range, the depth of penetration of dermal melanin can be measured.