The　effect　of　sample　tilt　in　spherical　indentation　is　studied　by　recourse　to　three-dimensional　finite　element　simulation　of　the　loading　process.　An　elastic　solid　subjected　to　a　rigid　spherical　indenter　is　considered　under　either　frictionless　or　infinitely　frictional　contact　condition.　It　is　found　the　contact　boundary　is　not　parallel　with　the　tilted　surface,　and　the　tilt　angle　of　the　contact　boundary　is　smaller　than　the　sample　tilt　angle.　The　side　force　is　prominent　for　frictionless　contact,　and　the　ratio　of　side　force　to　normal　force　increases　with　the　sample　tilt　angle　because　of　a　larger　unbalanced　displacement　field.　Nevertheless,　the　ratio　of　side　force　to　normal　force　is　relatively　small　for　infinitely　frictional　contact　because　the　displacement　distribution　is　controlled　by　the　nonslip　condition　and　almost　balanced　irrespective　of　sample　tilt.　Copyright　©　2018　by　ASTM　International.