A parametric stress analysis of T/Y and K square-to-square and square-to-round tubular joints subjected to axial loads, in-plane and out-of-plane bending moments has been performed using the finite element technique in order to provide a sound basis for using such sections in the design of complex structures. The results of this analysis are presented as a set of 42 equations expressing the stress concentration factor as a function of the relevant geometric parameters for various loading conditions. A comparison is made between the results obtained for square-to-square and square-to-round tubular joints and those obtained for round-to-round tubular joints by other researchers. In general, the stress concentration factors obtained from round-to-round and square-to-round tubular joints are closer as compared with those of the corresponding square-to-square tubular joints. Moreover, the stress concentration factors for square-to-square tubular joints are generally lower than those of the corresponding round-to-round and square-to-round tubular joints when the joints are subject to axial loads; but the reverse is true when the joints are subject to in-plane bending moments. However, the stress concentration factors for the three types of joint are comparable when they are subject to out-of-plane bending moments.