Hemingway attempted suicide in the spring of 1961, and received ECT treatment again. Some three weeks short of his 62nd birthday, he took his own life on the morning of July 2, 1961 at his home in Ketchum, Idaho, with a shotgun blast to the head. Judged not mentally responsible for his final act, he was buried in a Roman Catholic service. Hemingway himself blamed the ECT treatments for "putting him out of business" by destroying his memory; some medical and scholarly opinion has been receptive to this view, although others, including one of the physicians who prescribed the electroshock regimen, dispute that opinion.
Hemingway is believed to have purchased the weapon he used to commit suicide at Abercrombie & Fitch, which was then an elite excursion goods retailer and firearm supplier. (The shotgun was a Boss & Co ordered through A&F.) In a particularly gruesome suicide, he rested the gun butt of the double-barreled shotgun on the floor of a hallway in his home, leaned over it to put the twin muzzles to his forehead just above the eyes, and pulled both triggers. The coroner, at request of the family, did not do an autopsy.
Other members of Hemingway's immediate family also committed suicide, including his father, Clarence Hemingway, his siblings Ursula and Leicester, and possibly his granddaughter Margaux Hemingway. Some believe that certain members of Hemingway's paternal line had a hereditary disease known as haemochromatosis, in which an excess of iron concentration in the blood causes damage to the pancreas and also causes depression or instability in the cerebrum. Hemingway's physician father is known to have developed haemochromatosis (bronze diabetes) in the years prior to his suicide at age fifty-nine. Throughout his life, Hemingway had been a heavy drinker, succumbing to alcoholism in his later years.
Hemingway suffered from manic depression, now known as bipolar disorder, and was subsequently treated with electroshock therapy at Menninger Clinic. He later credited this to his memory loss which he cited as a reason for not wanting to live.
Hemingway is interred in the town cemetery in Ketchum, Idaho, at the north end of town. A memorial was erected in 1966. It is inscribed with a eulogy he wrote for a friend, Gene Van Guilder:
Best of all he loved the fall
The leaves yellow on the cottonwoods
Leaves floating on the trout streams
And above the hills
The high blue windless skies
Now he will be a part of them forever Ernest Hemingway - Idaho - 1939
Celebrating Hemingway's love for Idaho and the frontier, The Ernest Hemingway Festival  takes place annually in Ketchum and Sun Valley in late September with scholars, a reading by the PEN/Hemingway Award winner and many more events, including historical tours, open mic nights and a sponsored dinner at Hemingway's home in Warm Springs now maintained by the Nature Conservancy in Ketchum.