Union leaders did not make any speeches, saying it was their message after gathering 330,000 signatures in protest at the pension and health reforms and the latest hikes in petrol prices.
The rally was briefly addressed by President Stjepan Mesic, Deputy Prime Minister Damir Polancec and Mayor Milan Bandic, who extended their best wishes for International Labour Day.
Mesic said that Croatia was going in a good direction, but that a lot was to be done to reduce unemployment and increase wages.
"We have the opportunity, the potential and the will, but we must be better organised to attain the living standards of countries in whose company we want to be," the President said. "Austria has far less resources than we do, and they live in affluence while we live in poverty. Croatia should not allow this situation to continue," he added.
The three officials joined union activists in handing out free dishes of traditional thick bean soup to the crowd. Some 30,000 portions were distributed during the day.
Meanwhile, two trade unions took the occasion to stage another in a series of protests against what they called the illegal privatisation of the former Zagreb Tobacco Factory (TDZ), which is now owned by the Rovinj Tobacco Factory.
In the morning, several hundred workers and trade union members gathered in the central Ban Jelacic Square, from where they marched to the factory, criticising the government and other trade unions for doing nothing for the TDZ workers and urging the government to nullify the unlawful privatisation of TDZ.
Labour Day celebrations were also held elsewhere in the country.