  We discuss masses of stellar black holes found in binary systems and errors
in their determination. The observed mass distribution has a broad shape within
the range $4-16 M_\odot$ without visible concentration to some preferred value.
On the other hand, the black hole mass funciton as inferred from observations
of luminous X-ray sources in other galaxies exhibits a power-law form. We show
that both dynamically obtained black hole mass function and derived from X-ray
observations can be made consistent in the frame of the hypothesis of enhanced
black hole evaporation on a RSII brane for reasonable values of the warp-factor
of the Anti-de-Sitter bulk space.
