Bandmates Lars Ulrich, Kirk Hammett and Robert Trujillo posted on Twitter the shows would be called off.
Metallica has postponed its forthcoming tour of Australia and New Zealand as singer and co-founder James Hetfield has gone back into rehab.
The US heavy metal band was due to play concerts in Perth, Melbourne, Sydney, Brisbane and Auckland next month as part of their Worldwired tour.
Bandmates Lars Ulrich, Kirk Hammett and Robert Trujillo confirmed the cancellation on Twitter.
They said: «As most of you probably know, our brother James has been struggling with addiction on and off for many years.
«He has now, unfortunately, had to re-enter a treatment program to work on his recovery again.
«We fully intend to make our way to your part of the world as soon as health and schedule permit.
«Once again, we are devastated that we have inconvenienced so many of you, especially our most loyal fans who often travel great distances to experience our shows.
«We appreciate your understanding and support for James and, as always, thank you for being a part of our Metallica family.»