In order to perform leak-before-break analyses of nuclear piping systems and integrity evaluation of reactor vessels, full stress/strain (σ- ) curves and fracture resistance (J-R) curves for the concerned materials are required. However, it is time-consuming and expensive to obtain the J-R curves experimentally. The objective of this paper is to develop two methods for theJ-R curve prediction from tensile data. In the first method, elastic-plastic finite-element analyses for a series of crack length/specimen width values are performed. The load versus load line displacement curves corresponding to the fracture strain are obtained, and the J-R curves based on the generalized locus method are developed. In the second method, the correlation between σ- curves and J-R curves is statistically analyzed and an empirical equation for the J-R curve prediction from the tensile data is proposed. A good correlation between the predicted results from both proposed methods and experimental data is obtained.