The paper analyses results after investigation of color perception in 520 children (264 boys and 256 girls), aged 3-5 years, by means of two simple tests: a "Pflüger-Trident Test" (Velhagen) and a "Simplified Test of Color Vision" (Fletcher). It is proved that in children of under school age color perception is already developed enough and can be investigated for detecting disturbances in color vision.