Reinforced concrete members with circular cross-section are widely used in bridge engineering, either as piers or as piles to support pile caps. Such members are often subjected to combined shear, bending and axial loading. Compared with the overwhelming studies of shear in rectangular members, relatively few theoretical studies of the shear resistance of circular members can be found in the literature. This paper presents a model that can be used to predict the shear strength of circular members. The model is an extension of the plasticity-based crack sliding model originally developed for rectangular beams. Analytical solutions for simply supported and restrained members are presented. The results obtained by the model have been compared with a large number of tests. Satisfactory agreement has been found.