As a result, the band announced that it is postponing its upcoming tour of Australia and New Zealand.
RELATED: Rapid Fire: Metallica's Lars Ulrich
The band says lead singer James Hetfield has re-entered a treatment program for "an addiction." And that It's something he's struggled with on and off for years.
The band is promising to make its way back down under as soon as Hetfield's heath improves-- and their schedule permits.
RELATED: First Chase Center event brought traffic, excitement and news about Metallica's upcoming album
All tickets will be refunded.