The results of the evaluation of the lightfastness of the spruce wood treated by different shades of Drevodekor during the three years weather exposure in Strba are presented in this paper. Color changes were evaluated subjectively i.e. visually by the 5-step grey scale and objectively by measurement of the total color differences (CIE LAB 1976) using the trichromatic colorimeter DFC 5. By the subjective and objective methods of evaluation it was found, that the smallest color changes were determined on the specimens of spruce wood treated by Drevodeker shade Palisander, then followed the shades Mahagon, Jedlová zelen (green) and Pinia (yellow). By the differentiation of the quality of different shades of Drevodekor due to the different time of weather exposure it was found, that starting after the fifth month of exposure the same results were obtained both by subjective and objective evaluation. This means that for the given set of specimens the minimum time of radiation was 5 months. The resulting value of the exposure testing, which gives evidence about the relative quality order of the tested specimens, undergoes no further changes during the prolonged exposure.