One elderly patient has died and five others are being treated in hospital after developing flu-like symptoms at a ward in St Ita's psychiatric hospital in north Dublin.
The seven patients, who were all elderly, became ill between March 6 thand 12 th.
One woman was transferred to Beaumont Hospital on March 16 th, where she died the following day.
Six other patients were also taken to Beaumont. Five are said to be in a stable condition, while one is in the intensive care ward. One patient was transferred back to St Ita's.
They were diagnosed as suffering from Type A influenza, which is an acute virus of the respiratory tract.
The HSE said "all precautionary measures" have been taken and infection control and visiting restrictions are in place at St Ita's. It said there are no other cases at the hospital.
The HSE also expressed its sympathies to the family of the dead woman.