In this study, parameters which define Drucker-Prager yield criterion were investigated experimentally for both normal strength concrete (NSC) and high strength concrete (HSC) by triaxial compression tests. Total 16 concrete series with different concrete strength were produced. While 8 concrete series were produced as NSC (20 MPa < f(cm) < 55 MPa), other 8 series were produced as HSC (55 MPa < fcm < 85 MPa). Each series contains 16 specimens. Triaxial compression tests were performed on these concrete specimens. Concrete compressive strength of the specimens were measured under 4 different lateral compression level (0, 1, 2 and 4 MPa). After Mohr circles were drawn by using the data obtained from triaxial compression tests, the values of cohesion were determined between 5 MPa and 13 MPa for NSC and 13 MPa and 19 MPa for HSC. The values of internal friction angle were also obtained between 27 and 34 for NSC, 34 and 39 for HSC from the Mohr circles. The parameters defining the Drucker-Prager yield criterion were determined by using the values of cohesion and internal friction angle. Finally, after some equations were proposed to calculate the parameters by using concrete compressive strength, the validation of these equations were also proved in this study. (C) 2016 Elsevier Ltd. All rights reserved.