This paper deals with the strength of joints combining adhesives with bolts. The stress distributions in the adhesives and the variation of the bolt axial force were analyzed using an axi-symmetric theory of elasticity when an external tensile load was applied to the combination joint, in which two pipe flanges or two circular flanges were joined by adhesives, were clamped by nuts and bolts with an initial clamping force after they were joined by the adhesives. In addition, a method to estimate the strength of combination joint is proposed. Experiments were performed. The analytical results are consistent with the experimental results concerning the variation of the bolt axial force and the strength of joints. It is seen that the strength of the combination joint is greater than that of the adhesive joints and it increases with a decrease of the bolt pitch diameter. Furthermore, it is seen that the sealing performance of the combination joint, where the adherends are pipe flanges, is improved.