The experiment was conducted at Mushroom Research Laboratory Vegetable Crops Department, Faculty of Agriculture Cairo University, Giza and Regional Center for Food and Feed, Agricultural Research Center, Ministry of Agriculture Giza, Egypt during the two successive seasons of 2019/2020 and 2020/2021 under the environmental control of growth chamber. In this study, of oyster mushroom (Pleurotus columbinus) was used to evaluate the effect of adding prickly pear peel to the rice straw as the substrate for mushroom production comparing to rice husk additive on growth, yield and quality of mushroom. According to the results rice straw +200 g rice husk can be recommended as additive to rice straw substrate for oyster mushrooms production because it produced the highest cumulative numbers and weight of total and marketable fruits having high quality, represented in high contents of protein%, fiber%, P, Ca, Fe and essential amino acids, while rice straw +100 g rice husk can be recommended for high fruit yield and short harvesting period.