The main objective of this study was to investigate the behavior of reinforced concrete beams strengthened with external CFRP sheets. For this purpose, seven reinforced concrete beams with the same dimensions (1800 x 300 x 200 mm) and the same flexure and shear reinforcement were prepared and tested under combined shear and torsion with different strengthening configurations. The main parameters were the strengthening configuration and the CFRP sheet width. Three Strengthening configurations of the CFRP sheets were considered: one face bonding, C-shaped, and full wrapped. Two CFRP sheet widths were considered: 30 mm and 80 mm. From the experimental study, it was found that the contribution of external CFRP strips to the torsional strength varied from 3.2 % to 15.7 % for one face bonding, from 21.1% to 60% for C-shaped and from 20.6 % to 61.7 % for full wrapped. This showed that C-shaped configuration was sufficiently effective. Also a numerical analysis using ABAQUS software program was conducted by modeling the seven RC beams with and without external CFRP sheets. The numerical results were in good agreement with the experimental ones.