Organophosphorus inseclicide phosphamidon-degrading bacteria were isolated from agricultural soils and identified using Biolog microtiter assay. All Gram-positive degrading bacterial strains belong to genus Bacillus and many Gram-negative bacteria were rare soil species. Among them fast growing strains on phosphamidon-containing minimal medium were sclected and their biodegrading capability wcre measured. YD-17 which was identified as Capnocytophaga gingivalis showed the highest biodegradation rate. It could incrcase the removal of phosphamidon up to 52%. During the biodegradation continuous increase of amount of cell protein was observed, which indicated that phosphamidon was utilized as a carbon source for phosphamidon-degrading bacteria.