The rupee today lost 18 paise to 54 rupees 79 paise against the US dollar in early trade due to appreciation of the American currency against the euro overseas and a weak opening in the domestic equity market. Increased demand for the dollar from banks and importers also put pressure on the rupee. The rupee had closed 12 paise lower at 54 rupees 61 paise a dollar in yesterday's trade on heavy demand for the American currency.