The rupee fell by 43 paise to trade at 55.75, its lowest since July 13 against the dollar in early trade today at the Interbank Foreign Exchange as the American currency strengthened against euro and other currencies in the overseas market.
Dealers said apart from strengthening of dollar overseas on fresh concerns over Spain's borrowing costs and the fate of the euro zone, a weak opening in the domestic equity market weighed on the rupee sentiment.
Meanwhile, the BSE benchmark Sensex fell by 153.64 points, or 0.90%, at 17,004.80.
The rupee had lost 20 paise to close at 55.32 against the US currency in Friday's trade on weakness in local shares amid a firm dollar overseas as the euro zone debt problems resurfaced.