Excluding food and energy prices, which are more volatile, core CPI inflation in March was 0.2% and 2.3% one year.
Within three months of this year, inflation stood at 0.9 percent after rising 0.4% in February and 0.2 percent in January.
The fact that 12.7 million U.S. workers are unemployed and the income of those with jobs has grown very slowly makes it difficult for companies to raise prices of goods and services to consumers.
The data confirm that the Fed has room to maintain its policy of monetary stimulus that lowered the benchmark interest rate to less than 0.25% in December 2008 and has promised to keep it there until at least late 2014.
A 1.3% increase in the prices of used vehicles, the highest since December 2009, contributed to inflation as increases in clothing and medical care.
Energy costs rose 0.9% in March after 3.2% in February, and food prices last month rose 0.2%.