The Hsp70.2/Hst70 gene is a unique member of the 70 kDa heat shock proteins multigene family whose activity is regulated developmentally; in adult mice and rats its expression is restricted mostly to meiotic and postmeiotic male germ cells. In aim to analyze activity of the Hsp70.2/Hst70 promoter in developing embryos we have constructed transgenic mice expressing EGFP reporter gene under control of the rat Hst70 promoter. The appearance of EGFP fluorescence coincides with series of major developmental events, such as extra-embryonic membranes formation, axial rotation, formation of neural tube and the primordium of central nervous system, formation of differentiated somites, extensive remodeling of the heart, development of fingers and toes, and sensory organs formation. Activity of the Hst70 promoter localizes mostly inside nervous system indicating the role of Hsp70.2/Hst70 gene in development of this system.