The paper summarizes and analyzes the results of practical studies on the cultivation of Agaricus bisporus champignon mushrooms on a synthetic substrate with the introduction of organic additives into it – food and processing wastes: brewing waste, soybean and sunflower meal semolina. A yield analysis was carried out; indicators characterizing the quality of Agaricus bisporus mushrooms were studied; dependence of yield and quality of mushrooms on flush was demonstrated. It was noted that the preparation time of the substrate affects the number of flushes, respectively, and, correspondingly, on the yield of mushrooms: when growing mushrooms on a synthetic substrate prepared in the spring-summer period, two flushes are noted and, as a result, a higher yield is noted compared to mushrooms grown on a substrate prepared in the autumn-winter period. The study of the quality of fruit bodies showed that the use of additives increased the content of protein, fiber, fat and ash elements (potassium, phosphorus, calcium, sodium and magnesium). The results showed that the brewing waste is the best organic additive, which contributes not only to the growth of yield, but also to the improvement of the quality of cultured mushrooms. The study demonstrated that the quality of mushrooms obtained in the first flush exceeds the qualitative indicators of mushrooms grown in the second flush. The authors concluded that it is advisable to use organic waste (brewing waste, sunflower meal) as a substrate element when growing mushrooms in industrial conditions.