In　this　paper,　a　numerical　simulation　method　is　used　to　study　the　effect　of　specimen　size　on　interfacial　behavior　of　the　specimen　in　fiber　pullout　tests.　Interfacial　shear　stress　and　normal　stress　are　analyzed　for　different　sizes　of　the　test　specimen.　The　interface　between　fiber　and　matrix　is　assumed　to　be　bonded　perfectly.　For　simplicity,　all　materials　are　assumed　to　be　linear　and　elastic　solids,　and　the　effects　of　thermal　residual　stress　and　friction　between　crack　faces　are　ignored.　The　effects　on　interfacial　behavior　of　both　length　of　the　fiber　embedded　in　the　matrix　and　thickness　of　the　matrix　around　the　fiber　are　studied　using　the　finite　element　approach.　Furthermore,　the　effect　of　the　specimen　size　on　the　interfacial　crack　growth　is　also　studied　by　way　of　energy　release　rate.　The　study　shows　that　the　size　of　the　test　specimen　can　influence　interfacial　stresses　and　fracture　characteristics　dramatically.　(C)　2003　Elsevier　Science　Ltd.　All　rights　reserved.