The rupee strengthened marginally by 4 paise to Rs 51.86 per dollar in early trade on the Interbank Foreign Exchange on Thursday, supported by continued foreign fund inflows.
Dealers said consistent dollar inflows and selling of the American currency by exporters, mainly supported the rupee.
The rupee had lost 20 paise to close at Rs 51.90/91 per dollar yesterday on the emergence of dollar demand from importers.
Meanwhile, the 30-share BSE Sensex fell by 125 points, or 0.77 per cent, to 16,050.86 in opening trade on Thursday.
