Currently, low-grade and complex ores and mining wastes can be processed economically by using bacteria in heap and agitation leaching processes. Bacterial leaching tests are performed on the run-of-mine ore which is a mixture of two different massive and dissemine copper ores, fed to Küre Copper Plant. In this leaching process, using "Acidithiobacillus ferrooxidans" culture, bacteria count, pH, copper and iron recoveries are monitored during the 576 hours of test period. By increasing the solid ratio (1 %→5 %) the oxidation ability of bacteria decreases, thus the leaching rate. Therefore copper and iron recoveries decreased from 68 %, 35 % and 45 %, 20 %, respectively. As a result of laboratory tests, it is found that as the pulp density increased, the efficiency of copper recovery decreased using this bacterial culture.