Metal fatigue is a very important subject for which numerous contributions by P. K. Liaw are well-known. For crystalline metals and alloys fatigue leads to crack formation and failure, which can be catastrophic. Metallic glasses also fail by fatigue, but the microscopic mechanisms are different. In glasses defects, such as shear-transformation zones (STZs), are not topologically protected and disappear after activation. For this reason metallic glasses do not show work-hardening. Instead it is now known that the glass locally melts for a short time (~ ps) during the activation of STZ. This results in local rejuvenation to a more disordered ductile state. Therefore fatigue can lead to rejuvenation. However, shear bands and cracks formed by fatigue can shorten the life of metallic glass as a structural material. These should enter the alloy design strategy for better metallic glasses. This work is supported by the DOE-BES-MSED.