Yes. Section 406.3(D)(3) of the 2008 National Electric Code permits a non-grounding type receptacle to be replaced with a grounding type receptacle without a grounding connection. However, the grounding receptacle must be GFCI-protected. The diagram below shows a typical non-grounding (2-prong) receptacle replaced with a GFCI. The GFCI must be marked, No Equipment Ground. The GFCI can feed through to a grounding receptacle, which must be marked GFCI Protected. No Equipment Ground. For increased electrical safety, Leviton strongly recommends installing a GFCI in every non-grounding circuit. A ground wire provides protection by offering a parallel path back to ground for any fault current. Without a ground wire, fault current will try and take other paths to ground and a GFCI will trip and cut power under these hazardous conditions. Ground faults are more likely to occur in non-grounding circuits and a GFCI will help protect family members from this potentially hazardous condition.