We studied Cu-Zr-based alloys having exceptionally high glass-forming ability (GFA), and investigated the influence of Ag and A1 on the GFA and crystallization behavior. Most of the bulk glassy alloys studied do not contain any crystals in the as-solidified state. The crystallization kinetics of Cu 55Zr45, Cu50Zr50, Cu 55-xZr45Agx (x = 0, 10, 20), Cu 45Zr45Al5Ag5, Cu55Zr 30Ti10Ag5, Cu55Hf 25Ti10Ag5, Cu44Ag 15Zr36Ti5 and Cu45Zr 45Al5Ag5 glassy alloys was analyzed. Cu 35Zr45Ag20 alloy exhibits possible phase separation upon heating within the supercooled liquid region prior to crystallization. The depletion of Ag in the residual glassy phase results in the higher thermal stability of Cu35Zr45Ag10 versus Cu35Zr45Ag20, Cu50Zr 50 undergoes primary crystallization, forming a metastable monoclinic CuZr phase, while Cu55Zr5, Cu45Zr 45Ag10, Cu35Zr45Ag20 and Cu15Zr5Al5Ag5 undergo eutectic crystallization, forming mostly stable phases. Cu50Zr50, Cu55Zr30Ti10Ag5 and Cu 55Hf25Ti15Ag5 undergo nanocrystallization. Although some differences in the crystallization behavior between Cu55-xZr45Agx (x = 0, 10, 20) and Cu15Zr15Al5Ag5 were found, this may not be the only reason A1 and Ag additions improve the GFA of the Cu-Zr alloy. The difficulty in nucleating the tP4 AgZrss phase may be responsible for the high glass-forming ability of the Cu36Zr48Al 8Ag8 and Gu44Ag15Zr 36Ti5 alloys.