We calculate the binding energy of tritium using two relativistic versions of the Faddeev equations with separable potentials, and compare with the nonrelativistic results. We find that the relativistic effects increase the binding energy by less than 0.5 MeV. We do our calculations considering only S waves for the two-body interactions, but take into account the tensor force for different values of the deuteron D-state probability. NUCLEAR STRUCTURE Tritium binding energy, relativistic effects. © 1981 The American Physical Society.