McGrath is Test cricket's leading wicket-taking fast bowler

The 36-year-old told selectors he wants to remain in Australia to be with his wife Jane, who has cancer.

McGrath had already opted out of the Twenty20 international and the current one-day series in South Africa.

"Jane and family are still my priority at the moment ... so the cricket takes a back seat," McGrath told Sydney radio 2KY on Tuesday.

"To be honest, I've probably written the rest of the season off and I'll worry about cricket next season."

Chairman of selectors Trevor Hohns said he fully supported McGrath's decision and looked forward to seeing him play for Australia again in the future.

McGrath is Test cricket's most successful fast bowler ever, with 542 wickets in 119 Tests.

The tour of South Africa has already been hit by injuries to skipper Ricky Ponting (abdominal muscle strain), all-rounder Andrew Symonds (hip flexor strain) and Stuart Clark (rib bruising).

All three missed Sunday's opening one-day loss to the Proteas and are battling to be fit in time for Friday's second match in Cape Town.

The full squad for the three-Test series will be chosen and announced early next week.