Aviva is to increase its health insurance premiums by an average of 4% from next month.
It is the latest in a string of increases by insurance companies who blame the Government's health insurance levy and the rising cost of claims.
Laya insurance announced a 16% hike at the weekend, while the VHI raised its policies by an average of 6% last month.
Aviva said it regrets the hike, but that it is necessary to cover escalating claims costs and the levy.
From March 31, there will be increases of up to 6.4% on some plans, while others will not be affected.
Director of Irish Health Insurance Patrick Brennan said the Government's risk equalisation scheme is forcing the hand of insurers.
Mr Brennan said: "It is a case of damage limitation looking at your renewal every year rather than hoping to save money every year.
"That said, there are justifiable reasons for this and it is not always the big bad insurers. I think in this case you have to recognise that the Government, in setting up the new risk equalisation scheme due to come in at the end of the month, you will be seeing a €65 increase in the existing levy at the moment.
"So you are talking about the adult levy going from €285 to €350."