The interface microstructure and mechanical strength of joints obtained by diffusion bonding of alloy Ti-6A1-4V to AISI 316L stainless steel are presented. Bonding took place at 850, 900 and 950degreesC, maintained for different lengths of time (60 to 180 min). The highest recorded shear strength was equal to 382 MPa and was displayed by the specimen bonded at 950degreesC/180 min. Three different fracture paths were identified, each correlated to a characteristic strength range. From microprobe measurements and x-ray diffraction studies the following interface reaction products were identified: sigma phase, alpha-Ti, Fe2Ti, beta-Ti and Fe-Ti. The interface growth kinetics obeyed a quadratic law, indicating diffusion controlled growth of the beta-Ti layer. Finally, from correlations identified between beta-Ti layer thickness and shear strength variations, some hypotheses on the role of both pores and interface reaction product on mechanical strength were presented.