Vertical loads effect on the lateral response of a 3× 5 pile group embedded in sand is studied through a two-dimensional finite element analysis. The soil-pile interaction in three- dimensional type is idealized in the two-dimensional analysis using soil-pile interaction springs with a hysteretic nonlinear load displacement relationship. Vertical loads inducing a vertical pile head displacement of 0.1-pile diameter increase the lateral resistance of the single pile at a 60 mm lateral deflection by 8%. Vertical loads inducing the same vertical .