Measurement of Leptonic Structure Functions with the L3 detector at LEP

We report on a measurement of dimuon events obtained in a sample of single-tagged two photon events, at low Q2, between 0.2 GeV2 and 0.85 GeV2.The data were recorded by the L3 detector at LEP at center of mass energies between 189 GeV and 206 GeV. Production cross-sections and the leptonic structure functions will be presented.