We present some properties of the solutions to the Dirac equation with Woods--Saxon potentials. The results obtained for spherical nuclei are compared to those of the Relativistic Mean Field Theory. A possibility of very significant improvements in the description of single-particle properties is illustrated, and the corresponding choice of the parametrization is presented.

PACS numbers: 21.60.--n, 21.60.Fw, 21.10.Pc, 21.30.--x