A series of lightweight Ti–Zr–Be–Al bulk metallic glasses (BMGs) have been developed through the addition of Al to Ti–Zr–Be ternary glassy alloy. By replacing Be with Al, the critical size of the glassy rod has been increased from 5mm for Ti 41 Zr 25 Be 34 alloy to 7mm for Ti 41 Zr 25 Be 29 Al 5 alloy, while the yield strength of Ti 41 Zr 25 Be 34−x Al x (x=2–10) has been greatly enhanced, resulting in a significant increase of the specific strength which is defined as yield strength/density. Among these newly developed Ti–Zr–Be–Al BMGs, Ti 41 Zr 25 Be 26 Al 8 glassy alloy exhibits a high specific strength of 4.33×10 5 Nm/kg and a very large compressive plastic strain of 47.0%, which are much larger than those (3.69×10 5 Nm/kg and 2.9%, respectively) for Ti 41 Zr 25 Be 34 glassy alloy. The present results show that Al is an effective alloying element for improving the glass-forming ability (GFA) and mechanical properties of Ti-Zr-Be glassy alloy.