This work was carried out in Private Farm at Kaffer Saker, Sharkia Governorate, during the period between 2009 and 2010 seasons to study the effect of application with amino acids and vitamin B complex to the rice straw substrate on the growth, yield and its components, physical characters and chemical constituents of oyster mushroom fruit bodies.       The obtained results showed that, mushroom cultivated on rice straw +vit. B complex at 200 ppm + amino acids at 200 ppm gave the highest values of cap diameter, stipe diameter, stipe length and cap weight followed by rice straw + vitamin B complex 200 ppm. While, mushroom cultivated on rice straw + vitamin B complex at 200ppm gave the highest values of early yield/ bag, total yield/ bag, early yield / total yield % and biological efficiency% .                                                 On the other hand, cultivation of mushroom on rice straw + vit. B complex at 400 ppm + amino acids at 400 ppm gave the highest values of nitrogen , phosphorus, potassium, dry matter and crude protein as well as total carbohydrates followed by rice straw + vit. B complex at 200 ppm + amino acids at 200 ppm.                                                                                                    On the contrary, cultivation oyster mushroom on rice straw only (control) produced the lowest values of all studied characters.