C-Mn steels and associated welds can be susceptible to dynamic strain aging (DSA). In this case, fracture toughness passes through a minimum when the temperature increases from 20 to 300 o C. Since Charpy V-Notch data are not affected by the DSA phenomenon, the method for predicting the evolution of J 0 . 2 and dJ/da in the temperature domain where DSA occurs is still an open question. The purpose of the present study is the assessment of this decrease in fracture toughness using a local approach method. The results of J-R tearing resistance tests, characterized by crack initiation resistance J 0 . 2 and tearing modulus dJ/da relative to a base metal (A48 French standard steel) and manual metal arc deposited metals are presented and discussed. The local approach determination of J 0 . 2 was performed using the Rice and Tracey model. Comparisons between experimental results and the results of local approach modelling indicate that both J 0 . 2 and dJ/da decreases with DSA can be correctly predicted.