McIlroy said: "Having had a reaction to my earlier rib injury, I have been advised to take a conservative approach to my recovery which unfortunately means I have to withdraw from the BMW PGA Championship next week.
"It’s a disappointing decision to have to make, but I have to ensure I make a full recovery. I will now continue the process of preparing my game for the US Open and the rest of the season".
Keith Pelley, Chief Executive of the European Tour said: "There is no question that Rory will be missed at the BMW PGA Championship but his health is the most important thing and we wish him a speedy recovery."
The BMW PGA Championship