Bank of Korea governor Kim Choong-Soo and his fellow policymakers in a unanimous decision kept the seven-day repo rate unchanged at 3.25 percent for October.
"The rate freeze came on concerns that the gloomier global economic outlook will dent economic activities," Yoon Yeo-Sam, an analyst at Daewoo Securities, told Yonhap news agency.
"Korea's exports have weathered the global downturn well, but they are expected to slow down."
Seoul policymakers are battling to tame high inflation, but the September figures provided some respite. Consumer prices rose 4.3 percent that month year-on-year compared to a three-year high of 5.3 percent in August.
"The Korean economy is likely to be on track for long-term growth but downside risks to growth are dominant, given a weakening recovery in advanced economies and Europe's debt crisis," the central bank said in a statement.
It said consumer price rises were expected to slow but core inflation, which excludes volatile food and oil costs, would likely keep rising.
Governor Kim said last week the economy is expected to grow at a slower pace this year than the bank's earlier forecast of 4.3 percent, although it would still be higher than four percent.