Abstract: A model of elastic plastic half space indented by a rigid surface having a finite number of regularly spaced circular asperities was adopted to investigate the problem of multi asperity contacts. The contribution of multi asperity interaction to the contact stress was discussed. The plane strain multi asperity contact problem was computed using finite element method. It has been found that the deformation below the central asperity is mostly affected by the asperities near the center of contact. The effect of asperities remote from the center is relatively small. More asperities tend to interact with each other and affect the central contact zone in elastic plastic contacts as compared with elastic contacts. The change of spacing and radius of asperities and indentation depth would influence the asperity interaction.