Pile reponse to earthquake loading and soil–pile interaction behaviour were investigated experimentally using the hydraulic gradient similitude technique. The unique feature of this method is the application of a very high hydraulic gradient to increase the effective stresses in the model, simulating full-scale stress conditions in the field. The dynamic loading was applied to model piles using a conventional shake table. Tests on model piles embedded in dense sands are described herein. Both free vibration and forced vibration simulating earthquake loading were carried out. Pile bending moment, deflection, and acceleration were measured during testing. Dynamicp–ycurves were derived from the measurements and were found to be highly nonlinear and hysteretic at shallow depths under strong shaking. Thep–ycurves for low-level shaking showed essentially linear elastic behaviour. The experimentalp–ycurves were compared with the backbonep–ycurves for sand recommended by the American Petroleum Institute, and the agreement was reasonable except at shallow depths.Key words:pile, hydraulic gradient, modelling, vibration, shaking,p–y