The aim of this study was to i.) obtain Graphene (G)/epoxy, Graphene Oxide (GO)/epoxy, G/carbon fiber reinforced plastic (CFRP), GO/CFRP nanocomposites by G and GO addition to epoxy and CF matrices and ii.) investigate the effect of G and GO addition on tensile strength of the nanocomposites produced. The graphene was not homogeneously distributed in polymer matrices; therefore, the G was converted into the GO using hummers method. The characterization GO was carried out by SEM, EDX, FTIR and X-RD analysis, which confirmed the successful production of the GO. The G/epoxy, GO/epoxy, G/CFRP and GO/CFRP nanocomposites were obtained by adding G and GO to epoxy and CF at a rate of 0.1, 0.2, and 0.3%. The effect of G and GO on tensile strength of the nanocomposites was determined using a tensile test. The addition of G and GO at 0.2% rate yielded the best results. The effect of GO on tensile strength was better compared to that of the G.