Trade union leaders have called for support for the international day of action on 15 February to voice opposition to any war in Iraq.
Millions of people are expected to take part in demonstrations which will be held in capital cities around the world.
The Chairperson of the Anti-War Movement in Ireland, Richard Boyd Barrett, has said it is almost certain that between 50,000 and 100,000 people will lose their lives in the event of a war.
He expects that 20,000 will take part in the march in Dublin.
The Vice President of SIPTU, Jack O'Connor, says that his union's executives voted to affiliate to the anti-war movement, and he is urging members to support the march.
The General Secretary of ICTU, David Begg, says he is strongly convinced that this war is wrong.