Most of polycyclic aromatic hydrocarbons (PAHs) are highly toxic, mutagenic, carcinogenic and teratogenic in nature and exposure to these PAHs represents public health risks and raises environmental concerns. Signifi cant interest in the potential for bioremediation of PAHs on the contaminated sites has resulted in considerable progress in understanding biodegradation of PAHs and degradation pathways. Much of this research has focused on individual compounds, whereas on contaminated sites PAHs usually occur as mixtures of compounds. Four triplicate batch tests were used to establish the conditions for maximum degradation of naphthalene, phenanthrene and anthracene by changing the following four factors one at a time: temperature, pH, reaction time and pollutant concentrations. The optimal reactor conditions for the degradation of PAH, at the concentration of 1000 mg/L, were found to be 28ºC in pH= 7, under the reaction time of 7 days. The degradation of PAHs by these bacteria was confi rmed by GC-MS analysis and UV- spectroscopy. These bacteria were capable of degrading a mixture of PAHs with low and high molecular weight and degradation effi ciency was found tobe 57.1% for naphthalene, 82.1 % for phenanthrene and 55.2 % for anthracene at the end of 7 days. Fourteen types of bacteria were isolated and in 1000 mg/L of PAH destruction level, they achieved 3.3-82.1% of these compounds. Therefore this method is capable of removing PAHs from contaminated oily soil.