During his time as Prime Minister, Kirk kept up an intense schedule, refusing to reduce his workload by any significant degree and rarely taking time off (the Chatham Islands was his favourite retreat).
Kirk ignored advice from several doctors and from Bob Tizard and Warren Freer to "take care of himself" and to reduce his heavy consumption of Coca-Cola and alcohol (beer, plus later whisky or gin), saying he would have a "short but happy life".
 Though a non-smoker, he had diabetes and dysentery.

By 1974 he had difficulty in breathing, eating and sleeping.
In April he had an operation to remove varicose veins from both legs at once despite advice to have two operations.
Doctors and colleagues were urging him to take time off; on 26 August Social Credit leader Bruce Beetham advised him to take a couple of months off to recover.
His final public appearance was on 18 August to open St Peter's Catholic College in Palmerston North, when he stood in the rain for the whole ceremony, and he missed a proposed debate with Robert Muldoon before interviewer David Frost.

On 15 August 1974 he decided to take two days off, and on 26 August he decided to have six weeks of complete rest.
He had been checked over by many doctors, and an examination by Professor Tom O’Donnell on 27 August confirmed that he had an enlarged heart gravely weakened by embolisms, and which was not pumping regularly enough to get sufficient oxygen into his bloodstream; one lung was two-thirds incapacitated by the clot; and his stomach was very sore as his liver was swollen with retained fluid.
He went into the Home of Compassion Hospital, Island Bay, Wellington on 28 August.
He was photographed going in the boilerhouse door to avoid the media at the front.
He rang and reminisced with close colleagues, and his bed was covered with official papers.
On Saturday 31 August he told his wife Ruth, who had been told of his serious situation and came to Wellington, "I am dying .. please don't tell anyone".
Soon after 9 pm, while watching a police drama on television (Softly, Softly: Taskforce with Stratford Johns on NZBC TV), he slowly slid from a sitting position.
He died of a pulmonary embolism when a blood clot released from a vein into his heart cut off the blood flow and stopped the heart.
O'Donnell signed his death certificate.
Upon Kirk's death, Bill Rowling succeeded him as Prime Minister.

While colleagues had been urging him to take some time off, none were aware of the seriousness of his last illness.
Bob Harvey, the Labour Party President, said that Kirk was "a robust man" with the "constitution of a horse".
 He proposed a Royal Commission to investigate rumours that he had been killed, perhaps with contact poison, by the CIA.
This story returned during the 1999 visit of American President Bill Clinton to New Zealand.
During his time as Prime Minister, Kirk kept up an intense schedule, refusing to reduce his workload by any significant degree and rarely taking time off (the Chatham Islands was his favourite retreat). Kirk ignored advice from several doctors and from Bob Tizard and Warren Freer to "take care of himself" and to reduce his heavy consumption of Coca-Cola and alcohol (beer, plus later whisky or gin), saying he would have a "short but happy life".  Though a non-smoker, he had diabetes and dysentery.
By 1974 he had difficulty in breathing, eating and sleeping. In April he had an operation to remove varicose veins from both legs at once despite advice to have two operations. Doctors and colleagues were urging him to take time off; on 26 August Social Credit leader Bruce Beetham advised him to take a couple of months off to recover. His final public appearance was on 18 August to open St Peter's Catholic College in Palmerston North, when he stood in the rain for the whole ceremony, and he missed a proposed debate with Robert Muldoon before interviewer David Frost.
On 15 August 1974 he decided to take two days off, and on 26 August he decided to have six weeks of complete rest. He had been checked over by many doctors, and an examination by Professor Tom O’Donnell on 27 August confirmed that he had an enlarged heart gravely weakened by embolisms, and which was not pumping regularly enough to get sufficient oxygen into his bloodstream; one lung was two-thirds incapacitated by the clot; and his stomach was very sore as his liver was swollen with retained fluid. He went into the Home of Compassion Hospital, Island Bay, Wellington on 28 August. He was photographed going in the boilerhouse door to avoid the media at the front. He rang and reminisced with close colleagues, and his bed was covered with official papers. On Saturday 31 August he told his wife Ruth, who had been told of his serious situation and came to Wellington, "I am dying .. please don't tell anyone". Soon after 9 pm, while watching a police drama on television (Softly, Softly: Taskforce with Stratford Johns on NZBC TV), he slowly slid from a sitting position. He died of a pulmonary embolism when a blood clot released from a vein into his heart cut off the blood flow and stopped the heart. O'Donnell signed his death certificate. Upon Kirk's death, Bill Rowling succeeded him as Prime Minister.
While colleagues had been urging him to take some time off, none were aware of the seriousness of his last illness. Bob Harvey, the Labour Party President, said that Kirk was "a robust man" with the "constitution of a horse".  He proposed a Royal Commission to investigate rumours that he had been killed, perhaps with contact poison, by the CIA. This story returned during the 1999 visit of American President Bill Clinton to New Zealand.
Norman Kirk