This work was carried out during the period from 2006 to 2007 on a special farm at Kaffer Saker, Sharkia Governorate, processed for mushroom production, to study the effect of organic agricultural wastes substrates; i.e., rice straw, wheat straw, faba bean straw, cotton straw, maize straw, tomato straw, pepper straw, eggplant stalks, snap bean straw, pea straw, cowpea straw, groundnut straw and okra straw on the productivity of oyster mushroom. The results indicated that the suitable substrates used for cultivation and production of oyster mushroom were rice straw and wheat straw, which gave the highest values of yield and its components and dry matter contents of fruit body. As for chemical constituents of fruit bodies, fruit bodies produced on Fabaceae substrates (faba bean straw, snap bean straw, pea straw, cowpea straw and groundnut straw) had the highest values of nitrogen, potassium, protein and carbohydrates contents when compared with the other substrates.