The fatigue behaviour of six different hollow section T-joints subjected to out-of-plane bending moment was investigated experimentally using scaled steel models. The joints had circular brace members and rectangular chord members. Hot spot stresses and the stress concentration factors. (SCFs) were determined experimentally. Fatigue testing was carried out under constant amplitude loading in air. The test results have been statistically evaluated, and show that the experimental SCF values for circular-to-rectangular (CHS-to-RHS) hollow section joints were found to be below those of circular-to-circular (CHS-to-CHS) hollow section joints. The fatigue strength, referred to experimental hot spot stress, was in reasonably good agreement with referred fatigue design codes for tubular joints.