Russia's central bank has cut the key interest rate by 2 percentage points, to 15 percent, and the ruble lost value following the announcement.
The ruble fell below 71 per U.S. dollar and 81 per euro shortly after the surprise interest rate cut.
Russia's energy-reliant economy has been hit hard by the steep fall in world oil prices and the effects of Western sanctions imposed in response to Moscow's intervention in Ukraine.
The central bank had raised the rate to 17 percent in mid-December in a bid to halt the slide of the ruble, which lost about half its value last year.
Higher rates can bolster currencies but can hurt economic growth by making loans more expensive.
Explaining the reduction on January 30, the bank said the risks of an economic slowdown are greater than fears of a spiraling inflation.
