Sex and population differences in the ultraviolet (UV) reflectance patterns of two phenotypically divergent lacertids from Tenerife, Gallotia galloti eisentrauti and G. g. galloti, are described. Adults in both populations have rows of lateral and ventro-lateral blue patches on either side of the trunk that show a single peak of reflectance in the near UV. The lateral patches of males are more intensely reflective than those of females, but females have more chromatic and UV-shifted lateral patches than males. Most G. g. eisentrauti and some G. g. galloti also have blue cheek patches on either side of the gular area. Male cheek patches have reflectance peaks in the near UV, whereas those of females peak in the visible part of the spectrum. The lateral patches of males from the two populations differ in hue but not in intensity, those of G. g. galloti being more UV-shifted than those of G. g. eisentrauti. Female G. g. galloti have more intensely reflective lateral patches than female G. g. eisentrauti. Interindividual variation in peak wavelength and/or UV chroma is present in both sexes and populations. This is the first demonstration of sexual dichromatism in the UV reflectance of colour patches in a lacertid.