The deuteron tensor analyzing power T_2_0 in the deuteron break-up reaction D_p #-># pX is calculated within a relativistic approach based on the Bethe-Salpeter equation with a realistic meson-exchange potential. Our results on T_2_0 and the cross section are compared with experimental data and non-relativistic calculations and with the outcome of a relativization procedure of the deuteron wave function. (orig.)SIGLEAvailable from TIB Hannover: RR 1847(94-64) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman