Öz In this study, the effect of H2O2 (hydrogen peroxide) addition in the cyanide leaching of refractory sliver ores, obtained from ETİ GÜMÜŞ A.Ş. Aktepe district, is investigated. In the experiments, tpe effect of H2O2 concentration and leaching time on Ag recoveries of the silisified tuff (167 g Ag/t), silisified dolomite (47 g Ag/t), limonite-manganese (227 g Ag/t) and blended ore (175 g Ag/t) were examined. 10 g/l H2O2 addition in the grinding circuit had increased Ag recoveries approximately 19%. However, the same amount of H2O2 addition in the cyanide leaching of Aktepe silver ores had increased Ag recoveries between 10-15% according to ore type. As a result of this study, it was proved that addition of large quantity of H2O2 as an oxidant in the cyanide leaching of refractory silver ores had an increasing effect on the leaching recoveries of Ag