McGrath, the most successful Test fast bowler with 542 wickets, has not played a game of cricket since his wife Jane was rediagnosed with cancer on February 3.
But the 36-year-old said his wife, who was diagnosed with breast cancer in 1997 and has had three further recurrences of the disease, was now "very close to being back to 100 percent".
McGrath told Sydney's Daily Telegraph that his wife had encouraged him to go back to his sport, telling him: "Get yourself out to the cricket."
"I'm ready to go now, I'm back into training," he said.
"I've had a good break and my wife's going really well so it's always a good sign when she wants me back playing or wants me out of the house -- that means she's getting back to 100 percent."
McGrath said he hopes to make his comeback in the Champions Trophy one-day tournament in India in October as preparation for the Ashes series which begins in Australia in November.