Argentina's new president will either be elected outright in the first round of polling on 28 October or emerge after a run-off vote on 25 November - and will serve a four-year term.
Here is a guide to the main contenders:
CRISTINA FERNANDEZ DE KIRCHNER - FPV
The fact that President Nestor Kirchner's wife, Cristina, is bidding to succeed him has turned the presidential race more into a personality battle rather than a battle of ideas.
The current first lady is a an experienced politician, serving as senator for the province of Buenos Aires. She was appointed candidate for the Front for Victory (FPV) after Mr Kirchner decided not to run for re-election.
Cristina Fernandez de Kirchner is a politician in her own right
She has promised to continue his centre-left policies, but would probably be more active on the international stage than him.
If she wins, she will be the first woman elected president of Argentina.
Some of her critics describe her as an energetic person who does not like to be contradicted.
It looks very likely that she will win in the first round, the only question being whether she would get enough votes to avoid a run-off.
ELISA CARRIO - CIVIC COALITION
For Elisa Carrio, it will be the second time she is up against a Kirchner for the presidency.
In 2003, she ran against Mr Kirchner, winning about 14% of the vote.
Elisa Carrio says she not only older but wiser than in 2003
She has admitted that she feels liked "David" compared to Cristina Fernandez de Kirchner's "Goliath", but insists she is still confident of becoming Argentina's first elected female president.
The former federal deputy is a centre-left politician who is running on an anti-corruption platform and promising to reduce the gap between rich and poor.
Her Civic Coalition is a group of senior political figures from different parties who have joined forces for this election, espousing the principles of respect for republican values, ethics and income distribution.
ROBERTO LAVAGNA - UNA
Mr Lavagna was economy minister from 2002 to 2005, serving part of that time in Mr Kirchner's government.
He was the architect of the current economic model that rescued Argentina from its economic crisis and has led to 8% growth in recent years. He was also responsible for rescheduling Argentina's $100bn debt in 2005.
Roberto Lavagna has highlighted growing economic insecurity
Mr Lavagna, who is the candidate for the centrist Coalition for an Advanced Nation (UNA), says the government has lost its course and is undermining the economic successes of recent years.
In common with many other critics, he also says the government is lying about inflation statistics and not doing enough to fight social inequality.
RICHARDO LOPEZ MURPHY - RECREATE FOR GROWTH
Mr Lopez Murphy has previously served as economy minister and defence minister.
Representing the centre-right, Mr Murphy promises to create jobs and equal opportunities for everyone, and more transparent handling of government subsidies for unemployed workers and their families.
Mr Lopez Murphy has also criticised the government for not doing enough to tackle crime and insecurity.