The retrofit of reinforced concrete columns with FRP jackets has received considerable attention inrecent years. The advantages of this technique compared to other similar techniques include the highstrength-weight and stiffness-weight ratios of FRP (Fibre Reinforced Plastics), the strength and ductilityincrease of RC columns confined with FRP jackets as well as the fact that FRP external shells prevent ormitigate environmental degradation of the concrete and consequent corrosion of the steel reinforcement.Furthermore, this method also reduces the column transversal deformation and prevents the buckling oflongitudinal reinforcement.Twenty five experimental tests were carried out on reinforced concrete columns confined with CFRPcomposites, and subjected to axial monotonic compression. In order to evaluate the influence of severalparameters on the mechanical behavior of the columns, the height of the columns was maintained,while changing other parameters: the diameter of the columns, the type of material (plain or reinforcedconcrete), the steel hoop spacing of the RC columns and the number of CFRP layers.Predictive equations, based on the experimental analysis, are proposed to estimate the compressivestrength of the confined concrete, the maximum axial load and the axial or the lateral failure strain ofcircular RC columns jacketed with CFRP. A stressstrain model for CFRP confined concrete in compression,which considers the effect of the CFRP and the transversal reinforcement on the confined compressivestrength of the column is also proposed. The curves, axial load versus axial or lateral strain of the RCcolumn, are simulated based on the stressstrain model and include the longitudinal reinforcement effect.The results demonstrate that the model and the predictive equations represent very well the axialcompression behavior of RC circular columns confined with CFRP. The applicability of this model to alarge spectrum of RC column dimensions is its main advantage.