What time do polls close, when can we expect results?
Polling stations close across Argentina at 6pm local time (9pm GMT).
The first results are expected a few hours later, and exit polls sooner than that.
Exit polls by local television channels TN, C5N and América give Mr Fernández a lead over Macri.
However, local media did not release percentages following a ban on doing so under Argentine law.
Local media reported a court ruling prevents the results from being released until once the count reaches 10 percent in the four top districts.
The election pits Macri’s tough-love austerity against the “social contract” of the left-leaning opposition, whose populism has lured voters, hurt badly by a snarling economic crisis.
Mr Fernandez has a wide lead in pre-election polls, and one voter explained why he chose the opposition in this election.