  We briefly review a recently proposed formalism of perfect-fluid
hydrodynamics with spin, which is a generalization of the standard hydrodynamic
framework and provides a natural tool for describing the evolution of
spin-polarized systems of particles with spin 1/2. It is based on the de Groot
- van Leeuwen - van Weert forms of energy-momentum and spin tensors and
conservation laws. Using Bjorken symmetry we show how this formalism may be
used to determine observables describing the polarization of particles measured
in the experiment.
