It was the first time such prices have fallen in any month since 1982.
The tame report on consumer prices sent a positive signal to investors and borrowers. It suggested that short-term rates can remain low to strengthen the economic recovery without triggering inflation.
Some have worried that a Fed rate increase affecting consumers and businesses might be imminent, especially after it just raised the rate banks pay for emergency loans.
Friday's news helped reassure financial markets. The Dow Jones industrial average rose about 9 points, or 0.1 percent. Broader stock averages also gained modestly. Bond prices rose, pushing yields lower.
The Fed has kept a key bank lending rate at a record low near zero since December 2008. The goal is to entice consumers and businesses to boost spending.
Many analysts said the consumer-price report reinforced their view that the earliest the Fed will start raising rates is the fall. Some said the central bank might wait until the end of this year or early next year before raising its target for the federal funds rate. That's the rate banks charge for overnight loans.
"Rate hikes remain unlikely until late 2010 or early 2011," Eric Lascelles, an economist at TD Securities, wrote in a research note.
Overall consumer prices edged up 0.2 percent in January, the Labor Department said. But excluding volatile food and energy, prices fell 0.1 percent. That drop, the first monthly decline since December 1982, reflected falling prices for housing, new cars and airline fares.
The news was better than expected, especially after the government said Thursday that inflation at the wholesale level, excluding food and energy, rose 0.3 percent in January. That was faster than the 0.1 percent increase economists had predicted.
Chairman Ben Bernanke has said the Fed will likely start to tighten credit by raising the rate it pays banks on money they leave at the central bank. Doing so would raise rates tied to commercial banks' prime rate and affect many consumer loans. That would mark a shift away from the federal funds rate, its main lever since the 1980s.
The Fed announced late Thursday that it was boosting the rate banks pay for emergency loans by a quarter-point to 0.75 percent. That rate is called the discount rate .
The announcement of the discount rate increase initially roiled global financial markets. Investors feared it could be a signal that the Fed might start raising consumer and business rates because of inflation fears. The Fed increases rates to slow the economy and keep inflation pressures from rising too much.
But Friday's report of benign consumer prices calmed the initial market jitters. It solidified economists' belief that the central bank is still months away from any rate change that would directly affect consumers.
"The economy is still suffering from major problems," said Sal Guatieri, an economist at BMO Capital Markets. "The Fed is going to err on the side of keeping policy loose because of the high unemployment rate and the minimal risk that inflation will move higher over the next couple of years."
Guatieri said he thought September was the most likely time for the Fed to start boosting rates. Others predicted it would take longer.