Fiber Reinforced Polymer (FRP) bars represent an interesting alternative to conventional steel as internal reinforcement of Reinforced Concrete (RC) members where some properties such as durability, magnetic transparency, insulation, are of primary concern. Critical aspects of the design of FRP RC members are serviceability issues, bond, and the reduced concrete contribution to the shear capacity compared to equivalent steel reinforced members. The present paper focuses on the calibration of Eurocode-like equation for the evaluation of the shear strength of FRP RC members without shear reinforcement. The calibration is based on an extensive database of experimental data available in the literature. The concrete contribution to shear capacity is analyzed considering tested members without shear reinforcement and, with reference to Eurocode equation for shear capacity of steel RC members, a modified equation is proposed. A parametric analysis is presented comparing the results of the proposed equation with those given by both CSA and ACI guidelines.