Accumulation of obsolete pesticides in the environment is a global problem. The scale of the problem in different countries varies depending on economic situation and social awareness. Only limited data are available on the microbial biodegradation of fenitrothion. Biodegradation of fenitrothion by different microorganisms was investigated. Six bacterial strains were isolated from an agricultural soil and found to be actively utilizedfenitrothion,as a sole source of carbonand energy. Based on their morphological and biochemical categorization, the six bacterial and fungal isolates were identified as Pseudomonas sp., Trichoderma Viride, Brady rhizobium sp., Aspergillus niger,andAspergillus flavus. Results show that the degradation of fenitrothion by the selected microorganisms was in order Trichoderma Viride à Aspergillus nigerà Brady rhizobium sp. à Aspergillus flavus à Pseudomonas sp.,comparing to the control (degradation rate in media without microorganisms). Trichoderma viridereported that the highest degradation rate (t_1/215.64 days), followed by Aspergillus nigerand Brady rhizobium sp. with t_1/2 were 22.63 and 26.58 day, respectively. While the normal degradation in the culture media was reported as 76.41 days. Our results can conclude that these three organisms can be used to degrade the obsolete fenitrothion formulation.