Import prices fell 0.1 percent from November, with declines in fuel and non-fuel costs, the Labor Department said.
Export prices also fell 0.1 percent, with a 0.2 percent decline in non-agricultural export prices and a 0.1 percent gain in agricultural exports prices.
November's declines were generally sharper.
Fuel import prices were down 2.8 percent in November and 0.1 lower percent in December.
The decline in export prices was 0.7 percent in November and 0.1 percent in December.
Non-agricultural export price deflation also slowed month-to-month.
An 0.8 percent decline in November slowed to a 0.2 percent drop in December.
From December 2011 to December 2012, import prices dropped 1.5 percent, a turnaround from the prior 12 months, when import prices rose 8.5 percent.
Over the past 12 months, fuel imports followed the same pattern, falling 6.4 percent after rising 24.9 percent from December 2010 to December 2012.
Agriculture export prices have gone the other way over the past 24 months, with prices up 1 percent from December 2010 to December 2011 and up 12.8 percent from December 2011 to December 2012, the bureau said.