Thousands of teachers from around Portugal are marching in downtown Lisbon to protest proposed spending cuts they say will slash €1 billion ($1.3 billion) from the education budget.
Unions say the government plans to privatize many public schools and cut around 50,000 sector jobs.
Union spokesman Mario Nogueira says the plans revealed in a recent document from the International Monetary Fund would "mean the end of a free and inclusive public school system."
Portugal, which is headed for a third straight year of recession, needed a €78 billion lifeline in May 2011 to avert bankruptcy and has a jobless rate of 16.3 percent. Austerity measures have triggered many strikes and protests.
It was the third country that uses the euro to require an international bailout to deal with its debts.