Prime Minister Lee Hsien Loong paid tribute to pioneer unionists and called on Singaporeans to be grateful for their contributions.
He said these unionists played pivotal roles in Singapore's history such as defeating pro-communist groups and opening the economy to attract foreign investments.
He was delivering his annual May Day speech on Thursday at the Devan Nair Institute for Employment and Employability.
Mr Lee named several leaders such as Mr Tan Soon Yam from the Food Drinks and Allied Workers Union, Mr Abdul Rahman Mahbob from the Union of Power and Gas Employees Union and Mr Oscar Oliveiro from the Union of Telecom Employees.
Mr Lee recounted working with many of these senior unionists when he chaired the Economic Committee set up to help Singapore cope with the 1985 recession.
The committee made recommendations to the Government to cut CPF rates to reduce cost of doing business in Singapore.
"It was a difficult and painful exercise but they (pioneer unionists) helped convinced workers that it was necessary and partnered the Government to revive our economy and lead us out of recession," he said.