An experimental test series with seven beams externally prestressed with unbonded CFRP 7 (Carbon Fibre Reinforced Polymer) tendons has been performed. Presence of deviator, initial 8 tendon depth and prestressing force are varied. Results and behaviors are compared to 9 common beam theory, matching beams prestressed with steel tendons and a model taken 10 from literature to predict the beams behaviour. The test set-up include a newly developed 11 anchorage and post-tensioning system. From the evaluation it can be seen that CFRP and 12 steel tendons influence the strengthened beams structural behavior’s in similar patterns. The 13 small discrepancies is merely referred to different modulus of elasticity in the CFRP and steel 14 used in the tests. Predictions of load-deflection behaviour corresponded acceptable to 15 measured values while the stress experienced by the tendons was not as accurately modeled. 16 Deflection at failure is seen to be related to the number of flexural cracks formed within the 17 constant moment region.