  We present BVRcIc broad-band flux spectra for the host galaxies of GRB970508,
GRB980613, GRB980703, GRB990123 and GRB991208 obtained with the 6-m telescope
of SAO RAS. The BVRcIc of these hosts are best fitted by the spectral
properties of template SEDs of starburst galaxies and that there is a
significant internal extinction in these host galaxies. We derived the absolute
magnitudes of the GRB host galaxies making use of SEDs for the starburst
galaxies. We performed the population synthesis modeling of the continuum
spectral energy distribution of the host galaxies of GRB970508 and GRB980703
using different extinction laws and assuming burst and exponential scenarios of
star formation. The comparison of BVRcIc broad-band flux spectra with the local
starburst galaxies templates and theoretical templates as well as direct
estimates (using Balmer emission lines) of the internal extinction shows that
it is likely to be of great importance to take into account effects of the
internal extinction in the host galaxies. From the SED of the host galaxy of
GRB991208 and from the intensity of their spectral lines it follows that this
is a GRB galaxy with the highest massive star-formation rate of all known GRB
galaxies. The reduced luminosity of these dusty galaxies (e.g. for the host of
GRB970508 A_V\sim 2 mag, for the host of GRB980703 A_V\sim 0.6 mag and for the
host of GRB991208 A_V\sim 2 mag) could explain the observational fact: none of
the observed GRB host galaxies with known distances is brighter than the local
galaxies with the luminosity L_*.
