A lack of funding could see some health services in Northern Ireland disappear, according to the British Medical Association.
It said certain secondary care services were under threat after a move to streamline NHS administration in the region did not come with any added finances.
Dr Brian Patterson, chairman of the BMA's Northern Ireland Council, said nursing services in schools and community-based care programmes could be the first to go after the Review of Public Administration failed to deliver as expected.
He told the association's annual conference in Liverpool: "We are looking forward to the new streamlined structures delivering the promised quality health service.
"However, as we had feared, the Review of Public Administration did not release, in real terms, the promised tranche of money to reinvest in expansion of frontline services. The likelihood is that some services will disappear."
He said one area the NHS could save money was by employing less agency staff, arguing that expanding the normal workforce would result in less cost and more continuity of care for patients".
Dr Patterson added: "The reliance on the private sector both inside and outside Northern Ireland is hugely expensive, and we must find ways of delivering timely care without these luxuries, which we can't afford."