ACCELERATED microbial degradation of fenamiphos pesticide (nemacur) in liquid culture and uncultivated and cultivated soil by the efficient strains of Paenibacillus polymyxa, Pseudomonas fluorescens and Streptomyces aureofaciens were investigated. Fenamiphos amounts in liquid cultures of the three microorganisms decreased with elapsed time when it was used as a sole source of carbon and nitrogen. P. polymyxa proved to be able to decompose the pesticide at a higher rate than did Ps. fluorescens and S. aureofaciens. In pot experiment, soil amended with fenamiphos and inoculated with the aforementioned biodegrading strains showed higher values of N2- ase, dehydrogenase and phosphatase activity than uninoculated soil. The mixture of strains gave higher enzyme activities than when each strain was inoculated individually. Furthermore, soil cultivated with tomato showed higher activities of these enzymes than uncultivated soil. Uncultivated soil inoculated with only S. aureofaciens showed the most rapid disappearance of fenamiphos compared to soil inoculated with P. polymyxa, Ps. fluorescens or the mixture of the three organisms. However the rate of fenamiphos decomposition by the bacterial strains was higher in cultivated soil than in uncultivated soil, and cultivated soil exhibited the most rapid disappearance of fenamiphos with the mixture of the three strains. When soil samples were analyzed for the fenamiphos biodegradation after 22 days of the pesticide addition and 15 days after inoculation with the biodegradants, three metabolites of fenamiphos were detected. Results show that fenamiphos degradation can be effectively accelerated in soil by these microorganisms. Keywords: Biodegradation, Pesticide, Fenamiphos, Paenibacillus polymyxa, Pseudomonas fluorescens, Streptomyces aureofaciens, Persistence.