In September 2008, Dunne disclosed that he was being treated for bladder cancer. He was working on Too Much Money, his final book, at the time of his death. On September 22, 2008, Dunne complained of intense pain, and was taken by ambulance to Valley Hospital. Dunne died on August 26, 2009, at his home in Manhattan and was buried at Cove Cemetery in the Shadow of Gillette Castle in Hadlyme, Connecticut.