Extracts of the fruiting bodies of the Oyster mushroom (Pleurotus ostreatus) grown on wood substrates (beech, oak, linden, walnut, poplar) and extracts of the fruiting bodies of the Oyster mushroom (Pleurotus pulmonarius) grown in nature on aspen wood were used to determine the total phenols, total flavonoids, lycopene and β-carotene. The content of individual antioxidants varies considerably depending, not only on the substrate, but also on the extracting agents. The highest content of total phenols and total flavonoids was found in methanol and water extracts of the fruiting bodies of the Oyster mushrooms grown on oak and linden substrates. The maximum content of lycopene and β-carotene was determined in acetone and n-hexane (ratio 4 : 6) extracts of the fruiting bodies of the Oyster mushroom grown on an oak block. The results obtained in this study demonstrated that the quantitative and also probably the qualitative composition of the antioxidants in the fruiting bodies of Oyster mushrooms depended considerably on the substrate composition.