Age Action has said it is a "positive sign" that older workers are using legislation to protect themselves from discrimination by employers because of their age.
The comment comes after it was revealed the most common complaint to the Equality Authority under the Employment Equality Acts in 2007 related to discrimination on grounds of age.
The findings are contained in the authority's annual report, which is due to be published later today.
Age Action spokesman Eamon Timmins said it was "regrettable" that so many workers needed to go to the Equality Authority, but said it was a sign that older workers no longer willing to accept such discrimination.
"It is illegal under the Employment Equality Act to discriminate against somebody based on their age, and it is very encouraging that older workers are now using that legal protection," Mr Timmins said.
"However, we now need a sea change in attitudes among some employers."
Research carried out by Age Action last year found that 38 per cent of companies viewed the promotion prospects for workers aged over 50 to be less than for younger employees. This attitude was more prevalent in the public and retail sectors, where the figure jumped to 41 per cent and 40 per cent respectively.
Age Action's research programme concluded that compulsory retirement ages should be abolished, and that employers should consider part-time and flexible working arrangements for all staff. It also said that older workers should benefit equally from access to training, with courses aimed at professional and personal development.
Meanwhile, the Labour party's spokeswoman on equality, Kathleen Lynch, called on the Government to take action on the issues raised by the Equality Authority's report.
"We know the number of people over the age of 65 is set to double while the number of those over 85 is set to treble; yet nothing has been put in place to respond to this. Changes must be made and it is clear the Government is not changing to meet the challenge, so many of its policies towards older people are stuck in an out-dated mindset, today's report proves this," she said.
Ms Lynch said that, given the information contained in the report, it made no sense to to discuss merging the Equality Authority with Irish Human Rights Commission and the Data Protection Commissioner.
"All have their place and to dilute their important work in this way is ludicrous," she said.