Results of an investigation into the behaviour and capacities of tubular shear connectors for -precast and cast-in-situ composite construction in structural steel and concrete are presented. In precast composite construction the connectors are cast in the slabs at the precasting yard and on positioning the slabs over steel beams are welded to their flanges.Twenty-one push-out specimens were tested with continuously increasing and intermittently released static loading. The principal variables were (a) concrete strength(b) slab thickness(c) connector size(d) manner of load application.Attention was given to the examination of the effects of welding temperatures on the surrounding concrete and to the development of satisfactory welding techniques. Attention was also focussed on the selection of optimum and readily available shear connector sizes.Information was gained about the behaviour and the capacities of tubular shear connectors. Yield load has been defined as the capacity criterion and an equation as a function of the principal test variables is recommended for predicting the connector capacities. A comparison between the properties of shear connectors commonly used in cast-in-situ composite construction with those of tubular shear connectors is reported.Results obtained are not applicable when fatigue loading is involved.