The applied loads on structures caused by fault rupture can be divided into vertical and lateral loads. There is a common agreement between researchers that diagonal piles would performbetter than vertical piles under lateral loads. However, an area of uncertainty still remains: Would the diagonal piles still perform better under various load combinations? The 1999 Kocaeli earthquake was an appropriate case for monitoring the performance of vertical piles. In this paper, based on the evidence provided byKocaeli earthquake, a study has been done to compare the vertical and diagonal piles behavior. This study is conducted in two analysis steps. First, surface fault rupture is propagated through soil in the free-field. Second, the models of the piles group is subjected to a differential displacement the same as Step 1. Totally, it can be concluded that the acceptable performance of diagonal piles group occurs only when the fault emerges near the left center of cap. Otherwise, the vertical piles group would perform better.