Concrete-filled steel tube (CFT) members have primarily been used as beam-columns for the purpose of resisting compression or for combined compression and bending moment. Structural and constructional merits created demand for the use of CFTs as beam members under pure bending moment. Flexural strengths of CFT beam members are presented in many design codes but the related experimental studies are quite limited. This study compares the flexural strengths defined by design codes of AISC-LRFD, Eurocode 4, and AIJ and those from previous experimental tests. It is found herein that the flexural strengths of CFTs are affected by the size and shape of the tube section and material characteristics, and that depending on these factors, it is possible to overestimate the actual flexural strength of CFT beams. Therefore, this study underscores the need for additional data from full-scale CFT beam tests and for a systematic and thorough investigation of theoretical assumptions that underlie the sectional analysis of the design codes.