Gruevski is hoping for a landslide victory in order that he will not have to form a coalition government.
But violence blamed on the two main ethnic Albanian parties has dominated the run-up to polling and led to about 13,000 police being deployed across the country. Attacks reported
International monitors have recorded 13 reports of attacks against the Democratic Union for Integration (DUI), the largest ethnic Albanian opposition party.
Ali Ahmeti, the party leader, escaped unhurt after being shot at by an unidentified attacker on May 12. A bystander was injured in the attack.
"DUI was the target of provocation, of violence, of attacks, but we have never sought to retaliate because we refuse to submit to [violence]", Xhevat Ademi, a high-ranking party official, said.
Ademi said the rival Democratic Party of Albanians (DPA) was "nervous" because "DUI will win the elections". Ethnic Albanians make up about 25 per cent of Macedonia's population.
Imer Selmani, the outgoing health minister and vice-president of the DPA, said the DUI was frustrated at having been out of power for almost two years.
"Our political adversaries are presenting themselves as victims when in fact they never stop raising the threat of a return to 2001," he said, in reference to the year the minority fought a six-month insurgency against state forces which was ended by a western-brokered peace deal.
If Gruevski fails to win a landlside he is likely to need the support of the DPA or the DUI to form a government.
The DPA withdrew its support for his government in mid-March, in protest at its failure to recognise the independence of Kosovo, which stalled the government's efforts to continue with integration into the European Union.
The European Union and the United States called on Saturday for the elections to be "free from intimidation and in line with international standards".
But Radmila Sekerinska, the 35-year-old leader of the Social Democrats, has complained of fraud.
She alleged that posters appeared in Skopje, the capital, overnight intending to confuse voters into casting ballots for the wrong party as they mimicked her own posters but gave a different voter list number.
The electoral monitoring mission of the Organisation for Security and Co-operation in Europe (OSCE) has also registered complaints about a small party's voter list containing candidates with remarkably similar names to those on the Social Democratic ticket.
"It was clear that this is a scheme aimed at transferring some of the votes from our list to the governing list," Sekerinska said.
Nato entry blocked
The Balkan state had its entry to the Nato blocked in April by neighbour Greece after a dispute over Macedonia's name.
This added to a political crisis that led to the elections being called two years early.
Greece refuses to allow Macedonia to join Nato or the EU unless it changes its name, which Athens says implies claims on its own northern province of Macedonia.
Unlike the Social Democrats, Gruevski has rejected a name change and has vowed to put the issue to a referendum.
The mainstay of Gruevski's campaigning has focused on national pride and the name issue.