beta-galactosidase from fungus Curvularia inaequalis was modified by a chlortriazin dye active bright-orange KH. The modified enzyme contained two molecules of dye per one molecule of protein. The incorporation of six sulfuric groups with remains of the dye resulted in a slight decrease of the acid protein isoelectric point. The catalytic activity of the modified protein remains practically unchanged. The coloured protein is firmly absorbed on anionites. Preparations of immobilized beta-galactosidase were obtained by adsorption on anionites.