Trevor Lunn, a long-serving Assembly member for the Alliance Party, tweeted on Friday night that he has “spent the last few weeks in the care of the NHS”.
Mr Lunn, who is 72, added that he will be in NHS care for “some weeks to come”.
He said: “I cannot praise the staff and quality of care highly enough, there are no words.
“We must support and value our Health Service, the best in the world.
Mr Lunn has been MLA for Lagan Valley since 2007, when he took over the Alliance ticket from veteran Trevor Lunn. He is also a former mayor of Lisburn.