Bond yields fell further after the Fed signaled a more cautious outlook for economic growth and cut its projections for interest rates, in a sign that it remains concerned about the health of the recovery.
Benchmark 10-year note yields fell to 1.916 percent, from a yield of 2.05 percent before the central bank's announcement.
Five-year and seven-year note yields hit nearly three-week lows of 1.477 percent and 1.797 percent, respectively, after the decision, while 30-year bond yields fell to 2.57 percent, from a yield of 2.61 percent earlier.
On the short end of the yield curve, three-year note yields dropped to 0.934 percent, the lowest since early February, after the start of Fed Chair Janet Yellen's news conference in the wake of the release.
"Asymmetric" risks to low interest rates suggest that it's best to wait longer to raise rates, Yellen told members of the press Wednesday, adding that she doesn't think its appropriate to provide calendar-based guidance.