[en] Carbofuran and diazinon are used for controlling pests in areas of intensive cultivation of economic valuable crops in Egypt. A series of experiments was conducted to examine short-term changes in soil bacterial and fungal populations after copmmercial carbofuran or diazinon application. Soil enrichment culture technique was used to isolate carbofuran or diazinon degraders which, can be used to decontaminate pesticide polluted soils or sites. The most active isolates were completely identified as Aspergillus flavus, A niger, A. terreus, Fusarium sambucinum and F. dimerum. Aspergillus flavus and A. Terreus showed highest ability to degrade diazinon even at high concentration (7500 p.p.m). Electron microscopy studies on the most active diazinon degraders showed that diazinon affected mainly on sporulation process and hyphal formation. Studing the physiological conditions effective for the diazinon degradation by A. flavus and A. terreus, the optimum pH was found to be 7, incubation temperature 300 C for seven days. Salinity over 3% highly decreased the diazinon degradation while the aerobic condition favorites it. Selected fungal isolates were able to utilize diazinon as sole source of C, N, P or S but their ability was maximized in complete medium containing all nutritional components plus diazinon