Abstract: The experimental investigation on the reliability of gear-tooth fatigue strength for through hardening steel 37SiMn2MoV was tested. The tests were carried out on a electro-magnetic resonance fatique test machine of type EMR-1603 (U. K). Four loading sbtrss levels (of 6 samples each) were conducted. Based on the test data, the R-S-N curves and the related equations were fitted. Finally, the limiting bending fatique strength σ_Flim of the 37SiMn2MoV gear-tooth under different reliabilities have been evaluated.