He told the Senate Banking Committee record low interest rates would still be needed to support economic recovery.
The Fed was also prepared to step in with "further policy actions" to boost the economy if needed, he added.
Investors reacted negatively to the comments, with the Dow Jones Industrial Average closing 1% lower.
But Mr Bernanke downplayed fears that the US could re-enter recession.
Some economists have questioned whether a withdrawal of economic stimulus measures could harm the US economy's recovery.
"Even as the Federal Reserve continues prudent planning for the ultimate withdrawal of monetary policy accommodation, we also recognise that the economic outlook remains unusually uncertain," Mr Bernanke said, in prepared testimony.
"[But] rising demand from households and businesses should help sustain growth," he added."
BBC News - Bernanke: US economy faces 'uncertain' time
Looks like the worlds economies are far from out of the woods yet if the US is still shaky
