Bacterial leaching of the copper dust emanating from smelting furnaces of Sarcheshmeh Copper Mine has been studied. The present procedure to treat the dust which consists of about 30% copper is included in its collection and sending back to the furnace. Regarding the considerable amount of copper oxide minerals in the dust, a sulphuric acid leaching process was performed prior to bacterial leaching. Shake flask experiments were run using a mixed culture of thiobacilli and the effects of some parameters such as culture medium and pulp density on copper extraction were studied. Copper recoveries in 5% pulp density of inoculated and control flasks after 22 days incubation were 87% and 38%, respectively. (c) 2005 Elsevier Ltd. All rights reserved.