Voting stations will be open from 7am until 8pm with the first opening their doors in Australia and the last on the west coast of the US.
In all 1052 polling stations will be open - 953 in Latvia and 99 overseas.
Experts are predicting the most likely outcome of the election is a government broadly the same as the current coalition, but the performance of newly-formed parties could have a major influence on how things shake out.
"At the moment there is a more than 50 percent chance that they will win the share they need to stay in government. This is still the most likely outcome," the University of Latvia's Dainis Auers told LSM.
Turnout will be crucial with the last elections' turnout of 59% in statisticians' sights.
Provisional results are due to be announced at 4pm on Sunday but a fairly clear picture of voting patterns is expected in the early hours of Sunday morning.