Abstract: Sixty bacterial strains (isolated from soil near different petrol pumps of Karachi city) were screened for hydrocarbon degradation. They were identified on the basis of morpho-cultural and biochemical characteristics and were found belonging to different genera including Staphylococcus, Corynebacterium, Bacillus, Proteus, Pseudomonas, Klebsiella and Escherichia. Four solid hydrocarbons including biphenyl, camphor, phenanthrene and naphthalene and four liquid hydrocarbons i.e. benzene, toluene, octane and heptane were used in this study. In the case of solid hydrocarbons a total of 17% degraded biphenyl, 8% degraded camphor, 8% degraded naphthalene and 10% degraded phenanthrene. In case of liquid hydrocarbons about 57% were able to degraded benzene, 55% degraded toluene, 48% degraded octane and 33% degraded heptane. About 89% isolates degraded both solid and liquid hydrocarbons while 11% could not degrade any of them. In order to locate the genes responsible for hydrocarbon degradation, curing experiments were performed using physical agent i.e. elevated temperature and the chemical agent i.e. acridine orange. Results of these experiments indicated that the genes are plasmid born. In vivo direct gene transfer (bacterial conjugation) experiments were also performed and it was shown that hydrocarbon-degrading plasmid genes are stably transferable to the competent recipient cells.