The present study was conducted to examine the behaviour of instrumented flexible piles in dry sans under lateral cyclic loading using centrifuged models. Considering load service conditions, the influence of the number of cycles of their amplitude and of the soil density on the pile cap displacement and the maximum bending moment of the pile is examined. An empirical law to evaluate pile head displacements at application point is proposed. From the bending moment profile recorded during loading, P-y reaction curves are identified. A reduction coefficient r (P-multiplier) is introduced to quantify the effects of cyclic loads on P-y curves.