Due to the mechanical properties of Fibre Reinforced Polymers (FRP), serviceability limit states (SLS) often govern the design of FRP reinforced concrete (RC) structures. This study investigates the short-term serviceability behaviour of FRP RC beams through theoretical and experimental analysis. The experimental results on deformations, cracking and deflections are discussed. Prediction models provide adequate values of the experimental response up to the service load; however, an increment of the experimental deflection is obtained with respect to that provided by cracked section analysis when the load increases beyond the service condition. A discussion on the main aspects of the SLS of FRP RC is introduced, including the influence of the different parameters affecting the stresses in materials, maximum crack width and the allowable deflection. A methodology for the design of FRP RC at the serviceability requirements is presented. This procedure allows optimizing the overall depth of the element with respect to more generalised methodologies, since it takes account of the specific properties of materials and the loading conditions.