More than half of the dead were women and children, according to aid agency Medecins Sans Frontieres (MSF).
Taiz has been the scene of intense clashes between Houthi rebels and pro-government forces, supported by Saudi Arabia and its allies.
The coalition began targeting the Houthis in March.
It wants to defeat the rebel group, which controls much of Yemen, and restore the government of exiled President Abdrabbo Mansour Hadi.
The conflict has killed about 4,000 people so far, nearly half of them civilians, according to the United Nations.
Seventeen of those who lost their lives in air strikes late on Thursday were members of the same family, MSF said.
A number of civilians also died in rebel shelling in Taiz.
"We call on the warring parties to stop attacking civilian targets, especially hospitals, ambulances and densely populated neighbourhoods," MSF said in a statement.
The Houthis - backed by forces loyal to the former president, Ali Abdullah Saleh - say they are fighting against corruption and marginalisation of their northern powerbase by Mr Hadi's government.
Sunni power Saudi Arabia alleges its Shia rival Iran is providing the rebels with weapons. Tehran and the Houthis deny this.
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Meeting the Houthis and their enemies
Yemen's humanitarian catastrophe
At least 65 civilians have reportedly been killed in air strikes by a Saudi-led coalition on the Yemeni city of Taiz.