Abstract. The purpose of this study is to determine the parameters influencing the life of single crystalline Cu-Al-Be shape memory alloys. A strong correlation is found between crystal quality and fatigue life. For that purpose, a special device located at ILL (Institut laue-langevin) in Grenoble is employed. This device is a hard X-ray diffractometer using a transposition at high energy of the Guinier-Tennevin method. Thanks to these X-ray studies, it is found that mechanical lifespan is very sensitive to crystalline quality. In presence of subn of the orientation of reticular planes around a mean value), the lifespan can be reduce by a factor of 10.