One million people are on waiting lists for acute hospital appointments, according to the Irish Hospital Consultants' Association.
They also say one in every five consultant jobs are vacant due to issues over pay and retention.
The IHCA national conference has heard that countries with similar population numbers have twice the number of consultant staff in their health systems.
It says six key health projects such are now under threat because of a lack of senior doctors.
The Children's Hospital, the National Cancer Care Progamme, the National Maternity Strategy; two major initiatives in urology and intensive care, and the National Mental Health plan are at risk, it says.
The organisation's Vice President, Dr. Gabrielle Colleran, says Scotland's health service is a good comparison.
Health Minister Simon Harris had been due to give the keynote speech at today's conference -- but pulled out at the last minute, citing a conflict in his schedule.
Labour Party Leader, Brendan Howlin says Simon Harris should have turned up.
"The notion that the Minister for Health wouldn't go and hear [from doctors] tells its own tale of how disconnected they are, or indifferent even, to the real needs of a health service that is under pressure."
