More than 25,000 of the spoiled votes in the Ireland South ballot were left entirely blank.
In all, there were approximately 40,000 spoiled ballots out of the 750,000 votes cast in the Ireland South election.
It means that roughly 5% of ballots in Ireland South were spoiled, with more than half of these entirely blank, indicating that voters went to vote but simply opted to vote in the local election or referendum but did not continue their vote to the European elections.
In comparison, approximately 4% of votes in the Dublin constituency were deemed invalid, numbering some 15,345. In Midlands-North-West, a further 21,628 votes were spoiled, totalling 3.5% of the number of votes cast.
Campaign teams at the count in Nemo Rangers GAA Club in Cork described the number of ballots left entirely blank as "disappointing".
After reviewing the spoiled votes in Ireland South, approximately 750 to 1,000 of the invalid ballots were returned to the counting process.
Returning officer Martin Harvey said that there was "a small number" of protest votes, as well as small amounts of ballot papers with additional writing, multiple first preferences or Xs in the ballot boxes.
There were also approximately 100 votes that were deemed to have improper stamps on them.
Approximately 10,000 of the votes were determined invalid on the basis that voters continued their preferences from one ballot paper to the next, so-called 'Kiely votes'.
Mr Harvey added that the number of spoiled ballots was not particularly unusual for a vote of this size.
Ian Dinan, campaign manager for Sean Kelly, said it is important for voters to make sure their voice is heard.
"Democracy is an important process that not everyone in the world enjoys," he said.
"We would like to see everyone voting. What is happening in Europe is very significant and it is important to take part in that process."
Ed Davitt, election agent for Green Party candidate Grace O'Sullivan, said that of a turnout of approximately 750,000, 25,000 blank votes is not a huge number.
"It is certainly more than we would have liked but it is not a disaster," he said.
"We are seeing similar numbers in Midlands-North-West and Dublin."
Mags Murphy, Sheila Nunan's campaign manager, said that it is 'confusing' that voters would go to cast a vote but opt to leave some ballots blank.
She added: "It is disappointing that people would come to a count centre and, given the number of candidates and the length of the ballot paper, that they still opted to just vote in the local elections."
Meanwhile, there were 971 invalid ballots in the mayoral plebiscite in Cork city.
Of these, 500 ballots showed no preference whatsoever and many of the remaining ballots had extra writing or messages of protest.
Among these was one ballot which was inscribed with the words "we can't afford it", while another had "vote for Dustin the turkey" written on it.