The massive turnout suggests opposition forces have been able to tap into fresh outrage against Ali Abdullah Saleh after his comments Friday that mingling of men and women at protests violated Islamic law.
A youth movement leading the anti-Salah protests called for mass demonstrations yesterday, dubbed a day of "honour and dignity" that brought out a strong outpouring of women.
A young woman first led anti-Saleh demonstrations on a university campus in late January, but women didn''t begin taking part in large numbers until early March. It was a startling step in a nation with deeply conservative social and Islamic traditions.
But Saleh has clung to power despite the near-daily protests and defections by key allies in the military, powerful tribes and diplomatic corps amid calls to fight poverty and open up the country's restricted political life.
Security forces have launched fierce attacks on anti-government marches to try to protect Saleh's 32-year autocratic rule over the impoverished and fragile nation in the southern corner of the Arabian peninsula.
In the capital, Sanaa, authorities opened fire with live ammunition and tear gas, witnesses said.
Mohammed el-Abahi, the head doctor at the protesters' field hospital, said at least 30 people were wounded, including two people hit by bullets.
In the southern city of Damar, at least 18 people were injured in clashes with police and security agents after they fired tear gas, said medical officials who spoke on condition of anonymity because of fears of backlash from authorities. An activist in the city, Abdul Rahman Ahmed, said shots were heard but it was unclear whether it was rubber bullets or live ammunition.
Elsewhere, more than 100,000 people took to the streets in Taiz, a hotbed of protests, and large demonstrations were mounted in the port of Aden and other cities.
Abdel-Malek al-Youssefi, an activist and organiser with the youth movement, said the latest protest wave could well be "the last nail in Saleh's coffin."