The country's largest health insurer, the VHI, is set to lose over €80 million this year.
The chief executive of VHI Healthcare, Jimmy Tolan, said that in 2009 the company would spend €170 million in meeting the health care needs of customers aged over 60. He said by the end of this year, the company will have lost almost 120,000 subscribers.
Speaking at the Oireachtas joint committee on health and children, Mr Tolan said: "These levels of losses are unsustainable in a highly competitive marketplace."
Last month, it was revealed that the number of people covered by private health insurance is continuing to fall, according to new figures compiled by the regulator for the industry, the Health Insurance Authority (HIA).
In a report to the Department of Health, the HIA said the numbers fell for the second successive quarter in 2009.
According to the new Health Insurance Authority report, there were 2,278,000 people insured by the various companies in the market in June this year. This represents 51.5 per cent of the overall population. The new data indicates the number of people covered by private health insurance has fallen by 21,000 since the end of last year.
The Health Insurance Authority report states that in December 2008 there were 2,299,000 people insured in the market. This represented 52 per cent of the population.