Prior to the two-month upswing, import prices had declined four consecutive months. Except for an upward climb in March, import prices have declined or been unchanged in nine of the past 12 months.
Similar to August, import inflation in September was largely due to rising fuel prices.
Export prices also rose in September, gaining 0.8 percent after rising 1 percent in August and 0.4 percent in July.
On a 12-month basis, price changes have calmed dramatically.
The annual import inflation index stood at 12.7 percent in September 2011. It dropped steadily each month through July, by which time it was in the negative with the annual import price index down 3.3 percent. It has risen each month since, climbing to minus 0.6 percent in September.
Import prices influence the overall consumer price index. Currently, import prices fall well within the U.S. Federal Reserve's target inflation rate of 2 percent or lower.
The Fed looks closely at core inflation, which includes prices with the volatile categories of food and fuel excluded. But increased fuel costs affect household budgets anyway.
In September, the price index for imported fuels rose 4.4 percent, a more muted rise than the 5.7 percent price hike in August.
While petroleum product prices pushed higher, natural gas prices fell 0.3 percent August to September.
On a 12-month basis, export prices followed a similar pattern, starting at a 9.4 percent annual inflation rate in September 2011 and bottoming out this summer at minus 2.1 percent in June. The 12-month rate climbed to minus 0.5 percent in September.
Prices for agricultural exports rose 1.1 percent in September, following a 5.2 percent gain in August.
Over 12 months, agriculture export prices are up 6.7 percent, pushed by a 24 percent climb in the price of soybeans, the bureau said.