1,349 people under the age of 65 are living in nursing homes, according to the HSE's latest figures.
This cost the state nearly 62 million euro last year - or an average of almost 900 euro for each resident every week.
The HSE says young adults with disabilities are only accommodated in nursing homes where there are no alternatives.
Minister of State for Disabilities, Anne Rabbitte, says the new figures are very worrying.
