Research on the utilization of waste newspaper using a mycelium of the oyster mushroom Pleurotus ostreatus was conducted. The mycelium and fruiting bodies grown in growing substrates were cultured during the studies. The growing substrates were composed of waste newspaper or wheat straw, and mixtures thereof. Utilization of the components of the substrates was evaluated as the degree of utilization and performance of the fruiting bodies. The effectiveness of utilization depended on the amount of waste newspaper in the substrates. The maximum utilization was observed in the 3:1 mixture of waste newspaper and wheat straw. No fruiting bodies were formed in the substrate containing waste newspaper alone. The performance of the fruiting bodies was observed to increase as the concentration of waste newspaper in the substrates decreased. Heavy metals were present in the fruiting bodies grown in the substrates containing waste newspaper. Their concentrations were higher than acceptable by applicable standards, and the fruiting bodies were inedible. The substrates after cultivation were enriched in oyster protein.