Yew (Taxus baccata. L) as a tree species native to Iran, has always been the center of attention due to the high amount of active components. One of these compounds is taxol (paclitaxel) which is effective in treatment of variety of tumors and cancers. Nowadays numerous advanced biotechnological methods such as tissue culture are in progress in order to increase the amount of compounds. In this study, to produce callus, both stem and leaf explants were cultured in vitro under different treatments in order to select the optimal medium condition in which better quality callus was produced in shorter time. Stem explants produced better callus and B5 medium supplemented with 20 g/L sucrose, 8 g/L agar, 0.5 mg/L 1-naphtaleneacetic acid, 0.4 mg/L kinetin, 2 mg/L 2,4- dichlorophenoxyacetic acid, 0.1 mM gluthatione and 500mg/L Casein was the more effective medium. To reduce tissue browning different antioxidants were tested and 0.1 mM gluthatione was selected as an effective agent that considerably reduced tissue browning process and also stimulated the callogenesis and growth of callus
