Thousands demonstrated in Budapest against an education reform that centralized the governance of schools.
Some estimates suggest as many as 10 000 people took part in the protest, despite the heavy rain.
Protesters argue moves by the government, which in the autumn of 2012 took away control on schools from local authorities tasking a centralized institution to oversee them, are making the system inefficient, also restricting the choice of textbooks, the current ones reportedly containing errors.
Some of the teachers wore checked shirts in a recent trend they say mocks the arrogance of Hungarian politicians, according to Der Spiegel.
They demand that the new "mega-institution", which oversees the work of the country's 120 000 teachers and which some of them call "a bureaucratic monster", be closed down.
Tuesday's demonstration has been the biggest since the autumn of 2014, when a controversial Internet tax bill was scrapped after tens of thousands took to the streets.
It has also been the third held by teachers since the beginning of the year.
Back in February, as many as 50 000 parents were reported to have kept their childred at home instead of letting them go to school on the last day of the month, in support of teachers.
Der Spiegel quotes opinion polls showing more than three-quarters of respondents back the protest.
The latest demonstration coincided with the March 15 national holiday, when Hungarians are celebrating the 1848-1849 War of Independence.