A relativistic theory of electron-atom scattering is developed for polarized incident electrons on unpolarized atoms. The general case of inelastic scattering is considered with the elastic scattering as a special case. Formulas for angular distribution and spin polarization of the scattered electron are presented in terms of angle-independent dynamical parameters. These dynamical parameters are given as linear sums of radial integrals, suitable for numerical computations. The connection with well-known formulas for elastic scattering is demonstrated. The analyzing power and polarizing power of the target are given generally for, the electron-impact excitation of atoms. Spin polarization of total scattered electrons with a definite energy is also presented.