"The matter has been referred to the coroner."
Counties Manukau District Health Board spokeswoman Lauren Young said the man had been called in to do work on the roof when tragedy struck.
"It's awful. It's a tragic accident," said Young.
"Our thoughts and condolences go out to his family at this time."
The man had worked at the hospital for a number of years.
She said his colleagues are shocked and deeply saddened and counselling has been offered to those affected.
The death has been referred to the Coroner but WorkSafe has not been notified about the death.
A spokesman said it was the duty of the business to notify the government department of workplace accidents.
A small area of the busy hospital was cordoned off, but it remained open to patients and was operating normally.