Ten samples from various Egyptian governorates were collected from previously chlorpyrifos (CP) treated agricultural soils, to examine their ability to CP degradation under lab conditions. Each sample was divided into two parts; one of them was sterilized to be used as a control (SS), and the other was left without sterilization (nSS) to reply study hypothesizes. All samples (SS and nSS) were treated with CP at 10 ppm. CP residues were examined by GC analysis after time intervals. Results showed that completely CP disappearance was occurred within 14-28 days in nSS treatments, while in SS treatments ranged between 5-7% of initial concentration during the same period. Chlorpyrifos degradation was characterized using half-life values (DT50) and degradation rate constant (K) values. To confirm these results, soil samples that had a high capacity for CP degradation were treated again by CP at 20 ppm. Results showed that the CP disappearance was faster compared to first nSS treatments where CP was completely disappeared within 7-10 days. Also, the SS treatments showed negligible pesticide degradation. This high degradation ability can be attributed to the presence of microorganism's that have the capacity to degrade the tested pesticide. Our data confirm that the repeated application of the same pesticide for several years on the same soil piece may be led to the adaptation of microorganisms to this pesticide. Further study will be required to isolate and characterize a CP degrader strains that can be used after that in remediation of CP polluted sites.