Senator David Norris has revealed he has cancer.
The former presidential candidate and gay and human rights campaigner said he has been undergoing treatment for a serious condition.
"I am currently undergoing medical management for a serious cancer condition," he said.
"I am extremely grateful for the superb treatment I have received from the team of consultants at St Vincent's Private Hospital as well as the nursing and general hospital staff."
Mr Norris said he had no issue discussing it publicly and insisted there should not be any stigma associated with the disease.
The senator, who has represented Trinity College for decades, said it is believed the cancer is related to viral hepatitis which he contracted from tainted drinking water in eastern Europe in 1994.
"I have no difficulty in making this information public in response to press queries because I believe that there should be no stigma attaching to cancer as a disease," he said.
"I continue to enjoy life and am looking forward to returning to my duties in Seanad Eireann over the next few days."
Earlier this month, in an interview on RTE Radio, Senator Norris revealed he was undergoing tests but that he had "no intention of croaking it".