The loonie was down 0.53 of a cent to 76.70 cents US. That's the lowest level since Sept. 1, 2004.
The dollar has been on a downward slide since last summer, when the price of oil started to weaken.
Oil prices dropped below the US$50 mark in trading Wednesday, settling at US$49.19, while gold lost US$12 to fall to $1,091.50 an ounce.
Compounding the loonie weakness was a decision by the Bank of Canada to cut its key interest rate last week.
The central bank's overnight rate target stands at 0.5 per cent.