Rwanda has begun the process that analysts say will grant President Paul Kagame a third term in office.
The citizens are voting in a referendum on a constitutional amendment to allow President Kagame to seek re-election.
Some 6.4 million citizens are eligible to vote on Friday, and around 37,000 Rwandans living overseas were able to have their say Thursday, December 17.
Rwandans are expected to vote overwhelmingly in favour of changing the constitution. The change will allow Mr Kagame to potentially remain in power until 2024.
He is seen by many as the man who stopped the genocide that caused the death of at least 800,000 Tutsis and moderate Hutus in 1994.
The referendum was scheduled earlier in 2015 after the parliament backed a proposal to amend article 101 and allow Kagame to run in the 2017 election.
He has been President of Rwanda since 2001 and, at present, is bound by the constitution to step down after serving two consecutive seven-year terms.
Kagame has said that he will make a decision on the future of his political career after the referendum.