Tunisia's Prime Minister, Mohamed Ghannouchi, announced his resignation on Sunday on state television, following a wave of street protests.
Critics have accused Mr Ghannouchi of being too close to the state's former government, toppled in an uprising last month, and of failing to enact reforms.
Mr Ghannouchi had taken over when President Zine al-Abidine Ben Ali resigned, but the protesters said he was too close to the former leader to be acceptable as the head of the interim government.
"My resignation will provide a better atmosphere for the new era," he said, adding he wanted to prevent more victims in the country's political unrest.
Three people have been killed and several people wounded in clashes between security forces and demonstrators since Friday over Ghannouchi's role in the interim government.
Tunisia is where the unrest began in earnest last year, after a young vegetable trader set himself on fire in protest at his standard of life.
The unrest quickly escalated and protesters across the country focused their anger on Mr Ben Ali, who had been in power for 23 years. He resigned, and fled the country, on 14 January, for Saudi Arabia.