The Health Minister said the child had swine flu
A child under the age of three who had been diagnosed with swine flu has died.
The Health Minister Michael McGimpsey said the exact cause of the child's death on Tuesday was not yet known.
The child was a patient of the South Eastern Health Trust but no further details have been released.
Two people from NI have died from swine flu. Last month, a baby with the virus died in NI, but the cause of death was a pre-existing heart condition.
Mr McGimpsey expressed his deepest sympathy to the family of the child.
"It is desperately sad when a child dies and my thoughts and sympathies are with the child's family," he said.
"I would ask everyone to respect the privacy of the family at this very sad time. No further information will be given out at this stage."
Northern Ireland's Chief Medical Officer, Dr Michael McBride, said parents who have concerns that their child may have symptoms of swine flu should contact their GP.
"For parents of children who may have been in contact with this child, I would like to assure them that if their child has no symptoms of swine flu and is otherwise healthy there is no need for antiviral treatment," he said.
On Friday, it was announced that a Northern Ireland woman suffering from severe complications linked to swine flu was airlifted to an English hospital for treatment.
Last Thursday, 61 new cases of swine flu were confirmed in NI, the highest weekly number to date.
GP and out of hours consultations in connection with the virus also increased, as did antiviral prescriptions.
The number of people hospitalised with the virus has increased by 124%.
There have now been 336 laboratory confirmed cases of swine flu in Northern Ireland since the beginning of the swine flu outbreak.
GP consultations have risen to 208 per 100,000 - the highest rate since the start of the enhanced influenza surveillance programme.
Dr McBride has said the ongoing increase suggested a second wave of the outbreak.