The　objectives　of　the　study　are　to　examine　the　possibility　of　existence　of　size　effect　in　eccentrically　loaded　high-strength　reinforced　concrete　(RC)　columns,　and　discover　the　confinement　effect　of　transversal　reinforcement　on　the　size　effect.　A　series　of　eccentric　compressive　tests　of　12　geometrically　similar　high-strength　RC　columns　with　different　structural　sizes　and　different　stirrup　ratios　were　conducted.　Two　groups　of　columns　with　and　without　stirrups　at　the　mid-length　were　utilized.　The　widths　of　the　square　cross-section　of　the　RC　columns　tested　were　between　200　mm　800　mm,　and　the　lengths　varied　from　900　mm　to　3600　mm.　The　behavior　of　the　RC　columns,　involving　the　failure　patterns,　the　nominal　compressive　stress-strain　relationships,　the　ductility,　the　nominal　strength　and　the　post-peak　behavior　of　columns　were　observed　and　explored.　The　presence　of　the　transversal　reinforcement　changes　the　failure　patterns,　improves　the　nominal　strengths　and　makes　the　post-peak　behavior　of　columns　less　brittle.　Compared　to　the　columns　with　stirrups　at　mid-length　of　the　RC　columns,　the　ones　without　stirrups　at　the　mid-length　present　a　stronger　size　effect　for　their　higher　brittleness.