Myanmar opposition leader Aung San Suu Kyi has called on the international community to help ensure November polls bring "genuine political and governmental change".
It came as campaigning officially started in the former junta-run country.
Some 30 million people will have the chance to vote – many for the first time in their lives – in the elections, the only nationwide polls contested by Suu Kyi's party in a quarter of a century as the nation emerges from decades of stifling military rule.
Suu Kyi hailed the November 8 vote as a "turning point" for Myanmar, which has been ruled by a quasi-civilian government since the junta loosened its grip on outright power in 2011.
"For the first time in decades, our people will have a real chance of bringing about real change. This is a chance that we cannot afford to let slip," she said in an English-language video message released by her National League for Democracy (NLD) party.
But the election build up has been dogged by concerns over error-riddled voter lists, restrictions on campaigning and the disenfranchisement of hundreds of thousands of minority Muslims.
Whatever the outcome, the military will also retain its bloc of a quarter of all parliamentary seats.
The vote is for seats in the country's legislature, with a president selected by the combined houses of parliament in the months after the vote.
But Suu Kyi is ineligible for the top political job because of a rule in the country's junta-drafted constitution that bars those with a foreign spouse or children – her sons are British.
The Nobel laureate, who was locked up for some 15 years by the junta for her political beliefs, urged the international community to monitor the elections and ensure people's "will has been respected in the way of genuine political and governmental change".
She also urged voters to think of future generations as they prepare to cast their ballots.
Ceremonies to mark the campaign launch were held at party offices across the country.
Near the NLD office in Yangon, taxi driver Htwe Han perused an array of party merchandise.
"If the election is fought honestly, I believe the NLD will win," he told AFP, reflecting a widely held view.
But observers believe strong participation from ethnic minority parties and rising Buddhist nationalism could dilute the NLD vote.
Some 90 political parties are contesting the polls in Myanmar, whose opening has seen investment pour in.