During thermomechanical treatment of austenitic stainless steel alpha' martensite and E; martensite form in the austenite matrix. The martensitic transformation and deforming existing together result a high elongation at the investigated steel belonging to the TRIP grades. The amount of alpha' and epsilon, martensite depends on the strain level as well as on the deforming temperature in this steel. In the course of thermomechanical treatments we measured the amount and texture of the existing phases at different temperature and strain. It has been stated that the martensites are dominant in low temperature range, they have a considerable amount, and the transformation from E; martensite to alpha' martensite also takes place. The amount of alpha' martensite increases by increasing the strain while the amount of 6 martensite shows a maximum. By investigating the relationship between the quantity of existing phases and the effect of texture, it has been stated that the transformation takes place in certain given plates in the textured matrix.