In the study, presented in this paper, a general approach to the reliability based limit analysis of laterally loaded piles is presented. In engineering practice uncertainties play a very important role. The aim of this study is to evaluate the lateral load capacity of a long pile when plastic limit analysis is considered. In addition to the plastic limit analysis to control the plastic behaviour of the structure, a bound on the complementary strain energy of the residual forces is also applied. This bound has a significant effect for the load parameter. The solution to reliability-based problems is obtained by a computer program which is governed by the reliability index calculation.