Annual growth of the European Central Bank's broad M3 measure fell back to 10.3% in March from 11.3% the previous month.
The figure was slightly below an average analyst forecast of 10.4%.
Loans to the private sector, a sub-indicator watched closely by central bankers, rose by 10.8% in March, down slightly from the February pace of 11%.
In November, the M3 indicator, which includes cash, overnight deposits, other short-term deposits, repurchase agreements, shares and units in money market funds and debt securities with a maturity of up to two years, stood at a record high of 12.3%.
It is a widely-watched indicator of medium-term inflationary trends in the euro zone economy, though experts have increasingly questioned its relevance.
The latest figures suggest that euro zone inflation is set to ease in the coming months.
Lobby groups and politicians have urged the ECB to cut its short-term interest rate of 4.0% in order to stimulate ailing economic growth, but the Frankfurt-based central bank continues to see the fight against inflation as its biggest battle.
