Considerable differences in lignin degradation by fungi of two ecological groups have been revealed. Xylotrophs cause a twofold decrease in the molecular weight of lignin. The degrading activity of saprotrophs is insignificant. Xylotrophs demethoxylate and oxidize lignin more rapidly than saprotrophs, showing a higher level of antioxidant activity. As follows from the comparison of the degrading and antioxidative effects, measurement of the antioxidant activity can be used in screening of fungi for the ability to degrade lignocellulose substrates.