The ECB's Mario Draghi and the IMF's Christine Lagarde both sounded warning notes at the World Economic Forum in Davos, countering the markedly more upbeat tone seen at this year's forum when compared to recent years.
"The jury is still out on whether the economy will improve," Mr Draghi said.
He added: "We haven't really seen a recovery on the real side of the economy."
Shares and many other investments enjoyed their best year since the crash last year and yields on European bonds are close to record lows in many countries as the ECB pumps money into Europe's economy and the euro crisis recedes.
However, unemployment remains stubbornly high and economic growth remains anaemic at best.
The recovery has prompted some other leaders to warn that celebrations may be premature.
German Chancellor Angela Merkel adopted a similar theme in a speech in Davos on Thursday when she said the benefits of austerity could take four years to take effect.
Yesterday, Ms Lagarde urged leaders to "keep the momentum", adding: "It is too early to relax."
Legendary speculator George Soros said Ireland had got a "raw deal" during the financial crisis.
The investor, who has complained several times about Ireland's treatment, said Iceland had done better than Ireland, despite having endured a much bigger banking collapse.
He predicted that Ireland would get a deal which involves the "minimum" possible to save the country.
Mr Soros has a good track record when it comes to predictions. He said in Davos two years ago that Ms Merkel would not let the euro collapse and slammed the conditions imposed on Ireland during the bailout as "unjust".
The man who made more than $1bn shorting sterling in the early 1990s also said the next two years would see further instability, even though the worst of the crisis was over.