  Expressions for the unpolarized differential cross section and for various
polarization observables in the lepton-deuteron elastic scattering, $\ell+D\to
\ell+D$, $\ell=e$, $\mu$, $\tau$, have been obtained in one-photon-exchange
approximation, taking into account the lepton mass. Polarization effects have
been investigated for the case of a polarized lepton beam and polarized
deuteron target which can have vector or tensor polarization. Numerical
estimations of the lepton mass effects have been done for the unpolarized
differential cross section and for some polarization observables and applied to
the case of low energy muon deuteron elastic scattering.
