Organic compounds present in plants have been used in various experimental conditions for dyeing tests aimed to develop safe and environmentally friendly temporary and semipermanent hair dyes. Yak hairs were used as a model for the colorimetric evaluation of red, yellow, blue, and brown shades conferred to hair by selected natural compounds. Two different sources for red, yellow, blue and brown shades were tested. Anthocyanins from mulberry fruits and alizarin emerged as promising candidates for red shades, anthocyanin-blue and curcumin for blue and yellow, respectively, and p-benzoquinone and juglone for browns. The influence of pH, dye concentration, soaking time, and medium in which the dyes have been dissolved or dispersed has been studied.