  In this small review we present the actual state the knowledge about
weighting black holes. Black holes can be found in stellar binary systems in
our Galaxy and in other nearby galaxies, in globular clusters, which we can see
in our and nearby galaxies, and in centres of all well-developed galaxies.
Range of values of their masses is wide and cover about ten orders of magnitude
(not taking into account the hypothetic primordial black holes). Establishing
the presence of black holes, and in particular the measurement of their mass is
one on the key issues for many branches of astronomy, from stellar evolution to
cosmology.
