Elliott Mintz told The Associated Press yesterday that Ono went to the hospital on the advice of her doctor. He said media reports that she had had a stroke were not true.
Ono, who turned 83 last week, arrived at the hospital and medical staff decided to admit her, Mintz said. But "It was nothing," he added.
He said Ono likely will be released from the hospital today.
Ono is the widow of John Lennon of the Beatles. A Fire Department spokesman said an ambulance was called to Ono's apartment building at 72nd Street and Central Park West in Manhattan around 9 pm yesterday.
Ono remained hospitalised last night at Mount Sinai West Hospital in Manhattan, the same hospital where Lennon was pronounced dead. At the time, it was called St Luke's Roosevelt Hospital.