This study was conducted during the period from 2014 to 2015 in Mushroom Research Laboratory (MRL), Horticulture Department, Faculty of Agriculture, ZagazigUniversity to determine the suitable organic supplementations that enhance the yield and fruit bodies quality of oyster mushroom(Pleurotus florida). The added organic supplementations were rice bran and wheat bran at rates of 5%, 10% and 15% (W/W) of each separately. The best favourable treatment for increasing both diameter and weight of both cap and stipe, number of clusters/bag, early yield and total yield was cultivation of oyster mushroom on rice straw supplied with 15% rice bran, followed by rice straw + 10% rice bran. The highest values of both average cluster weight and dry matter percentage were obtained when mushroom was cultivated on rice straw + 5% rice bran. In addition, rice straw substrate amended with 15% rice bran gave the highest values of biological efficiency percentage. Whereas, cultivation of mushroom on rice straw + 15% wheat bran produced the lowest number of clusters per bag and the lowest biological efficiency percentage, followed by rice straw + 5% wheat bran. On the other hand, growing of oyster mushroom on rice straw + 10% wheat bran recorded the highest values of N, P, K, crude protein and total carbohydrates in fruit bodies, whereas fruit bodies obtained from growing of oyster mushroom on rice straw + 15% rice bran contained the lowest value of potassium and total carbohydrates percentage.