The government says 16 of them are in Japanese and South Korean companies, according to reports in state media.
Labour Ministry senior official, Le Xuan Thanh, is quoted in the Vietnam News daily saying workers have walked out over wages, working hours, rest periods and social insurance.
The head of the ministry's labour relations team Nguyen Manh Cuong was quoted saying workplace unrest has risen in part due to a labour shortage in industrial parks and export processing zones around Ho Chi Minh City.
He says many workers have not returned from their home towns after the Tet traditional Lunar New Year holidays in mid-February.
Early last year a major wave of strikes hit mostly foreign-owned companies in Vietnam, with tens of thousands of workers downing tools in demand for higher wages and better conditions.
Mr Cuong says Vietnam needs to enforce labour laws and establish an agency to help workers and employers negotiate.
Labour unions independent of the ruling Communist Party are banned in Vietnam and industrial relations experts say that workplaces currently lack transparent arbitration mechanisms to settle labour disputes.
Activists of the banned United Workers-Farmers Organisation says police have arrested and jailed several of its members since November.