In dermatology, study of human skin colour is related to skin phototype (SPT) in which the Fitzpatrick's scale is the most used skin photo type classification. Assessment of skin response to UV for various reasons plays an important role in dermatology. This is however not easy to be performed because of two reasons. Firstly, skin areas may have different skin tone resulting in different reflectance spectra and secondly, different modalities may produce different reflectance spectra. We hypothesize that the underlying pattern of reflectance spectra must be similar regardless of the modalities use and the skin areas where it is obtained, for a particular person. An observational clinical study involving 21 participants with SPT III was performed to study the relationship between reflectance spectra of facultative skin colour and constitutive skin colour obtained using two different instruments namely spectrophometer and multispectral camera. The reflectance spectra is then modelled by different linear regressions over different intervals of wavelength (piecewise linear regressions). Results show that correlation between the modelled reflectance and reflectance obtained from different skin samples using different instruments is very high (R-squared >0.965). For this, it can be inferred that the reflectance model based on piecewise linear regressions is suitable to model SPT III. © 2011 Springer-Verlag.