On average women earn almost €250,000 less during their working lives than men doing the same job, according to ICTU assistant general secretary Ms Joan Carmichael.
She was speaking yesterday at the launch of a new initiative by congress to close the 15.5 per cent pay gap that still exists between men and women.
Ms Carmichael's figures are based on an 18-year work span.
"Many women have gaps in their working careers because of childbirth and childcaring responsibilities and these breaks have a major impact on potential earnings," she said.
"Over an 18-year work span, the average male would earn €242,570 more than his female counterpart."
The Irish Congress of Trade Unions chose International Women's Day to launch the Gender and Pay (GAP) project, which will continue until March 2004.
The Irish Business and Employers' Confederation has agreed in principle to co-operate with congress in identifying areas where gender-proofing policies can help tackle the problem.
GAP project manager Ms Mags O'Brien said research showed that many young women professionals "feel the argument has been won" and do not see the need for such campaigns.
However, older women, including professionals, "find out later on what an effect family and child commitments can have on their career".
Ms Carmichael agreed that "many people feel that after 30 years of equal pay legislation the battle has been won" but added that "equal pay is still a myth rather than a reality".
The gap in earnings is still over 15 per cent and the disparity is even greater when factors such as occupational pensions and employment patterns are taken into account.
While 53.7 per cent of men have job-related pension entitlements, this figure reduces to 38 per cent for women.
Over two-thirds of women are concentrated in low-paid occupations.
Over an 18-year work span, the average male earns €242,570 more than his female counterpart, due to a combination of lower pay rates and the effects of career breaks to meet family commitments.
As part of the GAP project, congress will train hundreds of union representatives "to push equal pay up the bargaining agenda".
"Women make up 45 per cent of our affiliated membership. It is appropriate that we launch this project on International Women's Day," Ms Carmichael said.