  The results of photoconduction study of the Peierls conductors are reviewed.
The studied materials are quasi-one-dimensional conductors with the
charge-density wave: K$_{0.3}$MoO$_3$, both monoclinic and orthorhombic TaS$_3$
and also a semiconducting phase of NbS$_3$ (phase I). Experimental methods,
relaxation times, effects of illumination on linear and nonlinear charge
transport, the electric-field effect on photoconduction and results of the
spectral studies are described. We demonstrate, in particular, that a simple
model of modulated energy gap slightly smoothed by fluctuations fits the
available spectral data fairly well. The level of the fluctuations is
surprisingly small and does not exceed a few percent of the optical energy gap
value.
