Abstract: The applicability of shear wave velocity for evalu ation of soil liquef action is discussed.The so-called "threshold shear wave velocity" correspond ing to the "threshold strain" is recommended for preliminary investigation.The goo d correlation between the shear wave velocity and the shear stress ratio causing initial liquefaction may be used to calibrate the values of shear stress ratio causing initial liquefaction obtained in laboratory by the in situ shear wave ve locities.Further study is required to ascertain a so-called critical shear st rain.