The increasing use of high performance concrete in civil construction demands better knowledge of the behavior of this material and the review of possible changes in the design of structural elements, like the size effect. The concepts of the theory of fracture mechanics for the analysis of structures started to be used in recent days. The fracture energy became an inherent property of the material, and it is basic for the control of the nominal flexural strength and the modulus of rupture. The main purposes of this dissertation are to achieve experimentally the fracture parameters for high performance concrete by performing stable tests, and to carry out a comparison with numerical and experimental results found in literature. The methodology used for determining of these parameters is introduced in the work.Stable three-point bend tests were conducted in notched beams made with unreinforced concrete. These tests comply with the specifications given by the RILEM 50- FMC committee. The beams were cast at PUC-Rio Structural Laboratory and the tests were conducted at the Technology Institute (ITUC) of this University. The tests were performed using crack mouth opening displacement control in a closed-loop servohydraulic Instron machine model 8502. The experiments involved the testing of 75 singlenotched beams with four different sizes with depths varying from 38 mm to 304 mm. The thickness of the beams was kept constant and equal to 38 mm. The concrete had a watercement ratio varying from 0.37 to 0.25 and compressive strength between 70 MPa and 90 MPa.