Tensile tests performed on unstable austenitic material lead to formation of martensite. Therefore, plasticity and transformation occur at the same time leading to inelastic strain and consequently internal stresses. The present work focuses on the stress distribution in each phase of a two-phase material with an evolving microstructure. Experimental results based on X-ray diffraction are presented to give a trend of the evolution of stress distribution inside austenite and martensite during a tensile test at -60degreesC. After unloading, first results show compression in martensite and tension in austenite. It is also noticed that mechanical anisotropy is enhanced in both phases.