By using the concept of the joint probability distribution of independent stochastic variables, this paper gives an analysis of the maximum total wave forces on pile groups due to irregular wave action on the basis of Ref. [ 1 ].Methods for calculating the maximum total wave forces on pile groups considering both the wave energy spectrum and the directional wave spectrum are also given in this paper. Special computer programs MAXTOTWAF-PGZ-1 and MAXTOTWAF-PGZ-2 are developed for the purpose of calculation. By using the concept of the joint probability distribution of independent stochastic variables, this paper gives an analysis of the maximum total wave forces on pile groups due to irregular wave action on the basis of Ref. [1]. Methods for calculating the maximum total wave forces on pile groups considering both the wave energy spectrum and the directional wave spectrum are also given in this paper. Special computer programs MAXTOTWAF-PGZ-1 and MAXTOTWAF-PGZ-2 are developed for the purpose of calculation.