More than 1,000 nurses are set to retire from the health service by next June, said Minister for Primary Care Kathleen Lynch.
She said she hoped many of those considering retirement might be persuaded to stay on and asked nurses who have emigrated to consider returning.
The Minister says she has told the Taoiseach about this and described it as “very, very challenging”.
The exodus of nursing staff would affect all areas of the health service, she said, but mental health would be hardest hit in the “looming crisis”.
Ms Lynch also criticised Minister for Agriculture Simon Coveney's "disloyalty" over his suggestion that Fine Gael could go into coalition with Fianna Fáil.
"Mind you, Simon is involved in two battles – one with Leo Varadkar and the other with the electorate."
Sinn Féin health spokesperson Caoimhghín Ó Caoláin TD expressed concern at the staffing crisis predicted by Ms Lynch.
“The Minister must ensure that the same service is not seen as something to be escaped from at first chance.
“We need to increase staffing levels and attract Irish graduates who have decided to work abroad over the past number of years, many because of the recruitment embargo and some, undoubtedly, who did not want to face or to continue to work in our flawed services,” said Mr Ó Caoláin.