Inflation in the 16 countries using the euro plunged to an all-time low in March.
The annual rate was 0.6 percent, that is half what it was in February.
That strengthens the case for a deep European Central Bank interest rate cut by 0.5 percent to one percent when policymakers meet on Thursday.
The ECB target for inflation is below, but close to, two percent.
Several bank officials have said it would take action to prevent inflation from falling too low even though there is no risk of deflation.