The paper represents the outcomes of a parametric experimental investigation on the performance of rotationally restrained steel columns in fire. This experimental programme is a part of major research project performed at the Fire Research Center, University of Ulster in collaboration with the University of Sheffield. As a part of steel frames, half scale steel columns were tested in fire under two values of rotational restraint 0.18 and 0.93 and one value of axial restraint of approximately 0.29. Each case of rotational restraint was tested under five loading levels 0, 0.2, 0.4, 0.6 and 0.8. The paper includes a comparison with the behavior of a steel column previously tested in fire under axial restraint only. The paper represents also a method of estimating the effective length of fixed end (partial fixity) columns tested under fire. (C) 2001 Elsevier Science Ltd. All rights reserved.