Interim President Michel Djotodia has quit under pressure from regional leaders for failing to halt inter-religious violence in the Central African Republic.
His prime minister Nicolas Tiangaye also stepped down after a summit in neighbouring Chad aimed at stopping bloodshed that it is feared could spread.
Djotodia was swept to power last year in the Central African Republic when a loose rebel alliance known as Seleka seized the capital Bangui.
Months of abuses by his mainly Muslim rebels led to the creation of Christian defence militia. Cycles of killings followed, leaving hundreds dead.
French and African Union peacekeepers have struggled to restore order.