Constitutional amendment would allow rival parties to form coalition government.
Voting has ended in Tanzania's semi-autonomous region of Zanzibar in a referendum that would allow rival parties to form a coalition government.
Officials said Saturday voting proceeded peacefully and results are expected within a day or two.
Just over 400,000 people were eligible to vote on the constitutional amendment, which was designed to end years of political strife that has marred previous elections.
Under the plan, two vice presidential positions would be created that would be split between the leading parties in parliamentary elections.
Zanzibar President Amani Karume and other members of his ruling CCM party urged residents to vote "yes" to the referendum. The measure also had support from leaders of the main opposition party, CUF.
Zanzibar gained independence from Britain in 1963, then united with Tanganyika the following year to form what became the republic of Tanzania.