Presently, in industry, the main amounts of copper are extracted by the pyrometallurgy methods, particularly for the sulphide ore. On the other hand, the hydrometallurgical methods have been so far well benefited for the oxide ores withi the scale of industry too, but because of some serious difficulties for the solubility of sulphides, the hydro processes for the sulphides have not yet found their applications in the industry scale. Nevertheless, many researchers have worked on this subject during the last decades, mostly in the laboratory scale. This research work has been planned to evaluate –principally- the effect of mechanical activation (as an affecting agent in increasing the leaching efficiency) and also some other parameters (i.e. the time of grinding, the time of leaching, the temperature and the effect of oxygen purging) affecting the efficiency of copper extraction from the concentrate. The copper sulphidic concentrate was taken from the Sarcheshmah Mine, and the leaching solution was 0.5 molar Sulfuric acid. The main conclusions from the current research can be expressed a follows: 1) The mechanical activatio (grinding) before the leaching process could increase the leaching efficiency quite obviously, but this effect reaches a limiting (optimum) value of time, after which the efficiency does not ascend any more, and even descend to the lower values. The XRD results for the concentrate samples which were related to different time duration of grinding showed that the most structural variations happened for the samples which had been activated for 6 hours , the time that we can accept as the optimum time. 2) The SEM photographs also revealed this fact that during the mechanical activation (grinding), two types of phenomenon can simultaneously occur: first, decreasing the particles size, as the primary purpose of milling; and second, the agglomeration of particles. As the main effect of agglomeratio is the reduction in specific area, so this effect can obviously descend the chemical reactions between the leach liquid and the concentrate material, resulting less efficiency for the copper extraction. However, this phenomenon can be accepted as the main reason for descending the leaching efficiency after the time duration of grinding reaches an amount which was about 6 hours in our experiments. 3) The leaching temperature could affect the leaching efficiency by two opposite effects simultaneously: ascending the leaching efficiency because of ascending the chemical reactions due to higher degree of temperature; and descending the reactio efficiency is attributed to the decreasing the amount of oxygen (necessary for the chemical reactions) within the liquid, as the higher temperature causes less solubility of oxygen. This effect is more pronounced for the temperature degrees close to