Objectives: the action of ipochloride of sodium and ethylenediamine tetra-acetic acid can effect on the dentin surface after an endodontic treatment. The effects of these substances might have on the shear bond strength of dentin bonding systems has not yet clearfy.Methods:The purpose of this study was to evaluate the micro-shear bond strength to human dentin of one commercially available resin bonding systems using 30sec. and 120sec.of etching and a self etching primer on dentine treats by NaOCl and EDTA. Eighty freshly extracted first molars were included and divided in 4 groups.Three groups were treated (TG) alternatively for 15 minutes by NaOCl 5.25% and 5 minutes by EDTA.The remain group(UG) was the control without receive any treatment. Shear bond strengths to dentin were determined according to ISO TS 1140550,1994.The first group(TG30) was echted for 30 secondsthe second one(TG120) for 120 seconds,the third by a Self echting primer(SEPG) (Optibond Solo Plus-Kerrhawe) the control group was echted for 30 seconds (UG).The adhesive Optibond Solo Plus(Kerrhawe)(DBS) was applied on dentin surfaces following manufacturers directions and light cured. 3.5 x 2.0mm cylindrical Point four (Kerrhawe)composite cylinders were sheared off (Zwick universal-testing-machine, 1mm/min) after thermocycling (5-55°C, 5000x). Pairwise comparisons among groups were made using the Mann-Whitney-U-test (p < 0.05). Median values and 25- and 75% quartiles were then calculated;Results:The result of treated group echted for 30seconds(TG30) showed the following result: 20.0 (12.9/26.0) while the TG120 showed 32.3 (20.9/37.9),third group(SEPG) 32.1 (27.5/37.1) and the control group showed 34.5(16.3/39.7.).Conclusions:The specimes treated by NaOCl and EDTA and etched for 30 seconds provided lower values in dentin compared to the others three groups. Treatments by NaOCL alternatively with EDTA on dentin surface decrease the bond strength of DBS. The overechting or using a self echting primer on the dentin surface treated increase the bond strength of DBS.