Security is tight across Bangladesh for elections to return the country to democracy after two years of a military-backed emergency government.
About 50,000 soldiers and 600,000 police have been deployed to guard against election fraud and violence.
Long queues formed as Bangladeshis began to vote at the country's 35,000 heavily guarded polling stations.
The frontrunners, the Awami League of Sheikh Hasina and Khaleda Zia's Bangladesh Nationalist Party (BNP), have ruled Bangladesh for years.
Both leaders were jailed for corruption but released to contest the vote. The two rivals have pledged to lower food prices, and to tackle corruption and terrorism in the nation of 144 million people.
Sheikh Hasina and Khaleda Zia have also both promised to end the confrontation, strikes and violent street rallies that have marked Bangladeshi politics for years. The two women alternated in power for 15 years until 2006.
Observers say there may be no clear winner in parliament.