Pollings stations opened in Ethiopia on Monday as Prime minister Abiy Ahmed's ruling Prosperity Party is widely expected to cement its hold on power.
The party that wins a majority of seats in the House of Peoples' Representatives will form the next government.
Close to 40 million people have registered to take part in the national and regional parliamentary elections.
But in a fifth of the country's constituencies, Ethiopians won't be able to cast their vote, as a result of insecurity and logistical issues.
In 64 of them, the vote was pushed back to September 6th. But officials have yet to set a date for Tigray's 38 constituencies.
The elections, which were delayed twice since last year, are now contested by members of the opposition, with some accusing Ethiopia's ruling party of harassment, manipulation and threats of violence, that echo abuses of the past.
Other prominent opposition parties have decided to boycott the election.
Abiy is facing growing international criticism over the war in Ethiopia's northern Tigray region, sparked in part because Tigray's now-fugitive leaders objected to Ethiopia postponing the election last year while citing COVID-19.
Tigray's former leaders, who are fighting Ethiopian forces and those from neighboring Eritrea, have reported fierce new combat in recent days.
Ethiopia's defense forces have called the fighting challenging because of the rough terrain. Thousands of civilians have been killed in what observers describe as drawn-out guerrilla war.
Meanwhile, outbreaks of ethnic violence have killed hundreds of people in the Amhara, Oromia and Benishangul-Gumuz regions in recent months.
International concern has been growing about the election. The U.S. has said it is "gravely concerned about the environment under which these upcoming elections are to be held", and the European Union said it will not observe the vote after its requests to import communications equipment were denied.
In response, Ethiopia said external observers "are neither essential nor necessary to certify the credibility of an election,'' although it has since welcomed observers deployed by the African Union.
The United Nations secretary-general has noted the "challenging'' environment and warned against acts of violence.
"It is our duty to remain united and not the government's,'' one resident of the capital, Eskedar Teklegiorges, said over the weekend as hundreds of police officers paraded in a show of force ahead of the vote.
Security forces were deployed in capital city Addis Abeba and in the country, to ensure a peaceful election.