By resoundingly rejecting the euro, Sweden's voters may hasten the advent of a two-speed Europe in which a core of member states of the single currency push ahead with integration leaving others behind, analysts say.
The sheer scale of Sunday's 56-42 per cent referendum defeat, despite almost the entire political and business establishment campaigning for a "yes", is bound to reduce any prospect of an early vote in Britain or Denmark.
The blow to Brussels' morale from the third lost vote in a member state in as many years will revive talk of the EU's "democratic deficit" and raise uncertainty about the prospect of ratifying the first EU constitution, due to be signed next May.
Several countries have said they plan to hold referendums and with the EU expanding from 15 to 25 member states next year, the risk of one or more voting "no" is greater.
"We will now have a semi-permanent group of "outs", none of which is likely to join the euro before 2010," said Katinka Barysch, chief economist at London's Centre for Economic Reform.
"That will reinforce the drive in the EU towards a two-speed Europe with closer cooperation in the euro zone on economics."
However, most experts say it is unlikely to slow the march of acceding countries in central Europe to join the euro, which many see as an anchor of monetary stability to underpin their investment-dependent economies.
Candidate countries continue to endorse joining the EU by unexpectedly big margins in referendums across central Europe, suggesting that voters in former communist countries know where their economic interests lie.
The European Commission's first reaction was to tell Swedes their country would lose influence by being outside the Eurogroup of finance ministers of the single currency, which is taking on an increasingly leading role in economic policy-making.
Analysts and EU officials said the euro zone had made itself unattractive to potential members in western Europe because of stagnant growth and wrangling over the excessive budget deficits of the biggest economies - Germany and France.
French defiance of the EU's Stability Pact limiting deficits increased the impression that there was one law for the big countries and another for smaller states - a bone of contention in the EU constitutional negotiations, too.
"Given the very bad shape of the euro zone, this poor image was probably decisive in Sweden," said Daniel Gros, director of the Brussels-based Centre for European Policy Studies.
Only when the big countries in the euro zone had carried out structural reforms to improve their economic performance would it become more attractive.
"They'll get their act together eventually, but not because of Sweden," Mr Gros said.
The stunning Swedish defeat reinforced the lessons of previous lost referendums in Denmark, Ireland and Norway, where disparate coalitions of largely leaderless "naysayers" defeated much better funded pro-European campaigns.
The EU, and especially the euro, are seen as elite projects, remote from ordinary citizens, uneasy about their national governments' perceived loss of control over policy.
"There is a widespread feeling that too much happens from the top down and not enough from the bottom up in Europe," said John Palmer, director of the European Policy Centre in Brussels.
The EU was in an awkward transitional phase from being a "top-down" organsation with little democracy, to developing pan-European democratic institutions and parties.
"We are half-way between the two and people don't yet see that they have real European choices. The question is whether the constitution can put in place a European political space with which people identify," he said.
However, Mr Palmer said voters would be less likely to vote "no" in a referendum on the constitution if they believed the alternative was having to leave the EU.