Abstract: Three Point Bend (3PB) bimaterial specimens of PMMA/PC were made by joining the two materials using friction welding. The specimens were tested and the crack initiation loads were recorded to evaluate the KIC using ASTM standard E 1820-01. Stress field in the crack tip vicinity was studied using finite element analysis of the specimen model. Normal and shear stresses were recorded for a series of nodes ahead of the crack tip at (θ=0 ° ). SIF values were calculated using these stress values and it was found that the stresses at a certain distance lying outside the process zone provide a SIF value matching to that of experimental fracture toughness of the specimen under study. Based upon the experimental evidence and finite element analysis, a simple step by step procedure is proposed to calculate the fracture toughness of bimaterials for a complex stress field.