Two names stand out from the long list of contenders: 44-year-old candidate Santiago Pena from the ruling conservative Colorado Party, which has been in power for over 70 years with a brief interruption in 2010s; and 60-year-old Efrain Alegre from the Authentic Radical Liberal Party. The latter ran for the top job in 2013 and 2018 and leads a broad coalition of 14 opposition parties in his third presidential bid.
In addition to the presidential race, Paraguayans are also electing vice president, lawmakers and governors on Sunday.
Polls are set to close at 4 p.m. local time (20:00 GMT), with the results of the single-round elections expected on the same day. Electronic ballot-box will be used during the Sunday's polls for the first time in the history of Paraguay's elections.
The next president will be inaugurated on August 15 for a five-year term.