The president and secretary general of the Zimbabwe Congress of Trade Unions are among several labor officials arrested before peaceful demonstrations were broken up by riot police in Harare and Bulawayo.
The demonstrations were against the rising cost of living and cheap imported Chinese goods, which unionists say are causing job losses in the manufacturing sector.
Unionists, many of them women, carried small posters saying "No to Zhing Zhong", which is derogatory Zimbabwe slang for Chinese goods. The demonstrators managed to walk around one block in the city center before scores of riot police, some of them armed, broke up the anti-poverty march and arrested about 80 people singing union songs.
Zimbabwe Congress of Trade Unions President Lovemore Matombo and his Secretary General Wellington Chibibe were among those arrested during the day. Earlier, police arrested at least three top unionists in second city Bulawayo, and detained a leading Harare civil rights activist.
Union leaders say their march was not political and therefore they did not need permission from the police to hold their demonstration.
The unionist demonstrators, who were watched by several hundred people, want the government to lower personal tax, stop imports from China, and make it possible for employers to pay workers more.
With inflation approaching 400 percent per year, and an increase in the cost of food of more than 80 percent in October, most workers say they can no longer afford to feed their families.
The Zimbabwe Congress of Trade Unions says it represents 30 worker organizations with one million members. But the union movement in Zimbabwe has been greatly weakened in the past six years as hundreds of thousands of workers have lost jobs as the economy contracted.
It is not clear what the arrested unionists have been charged with, but they could face charges of breaking Zimbabwe's tough security laws.