The buckling behaviour of T-section columns is discussed in detail followed by a numerical study using geometric and material (GMNIA) analysis to produce column strengths for a wide range of geometries of T-sections and column lengths. The T-sections are assumed to be hot-rolled and include residual stresses and geometric imperfections typical of hot-rolled sections. Based on the numerical strengths thus produced and available test strengths for T-section columns, the design provisions of the Australian, European and American Specifications for hot-rolled steel structures are evaluated. It is shown that while the Australian Standard provides fairly consistent and accurate predictions of strength, the design provisions for T-sections of current European and American Specifications are conservative and associated with large variability, particularly for T-sections with slender elements. The paper recommends modifications to the European and American specifications which improve the design strength predictions of these specifications for T-section columns. University of Sydney Research Report R932.