For laser propagation through an inertia! confinement fusion reactor target chamber there is a maximum for the allowable gas density and hence for the shot repetition rate in the chamber. Small angle forward stimulated Raman scattering (SRS) is an important process in limiting the propagation and setting this constraint. A conservative model — propagation of the laser beam through a uniform plasma with the plasma wave amplitude determined by saturation due to electron trapping — leads to a fractional energy loss which scales as the square of the wavelength and is independent of intensity. For a 10 MJ target in an argon atmosphere, it is expected that the onset of substantial energy loss will occur very abruptly as the gas density increases beyond about 10l6 cm−3; for a LiF/BeF2 atmosphere, the acceptable density of LiF molecules may be about a factor of three smaller (3 × 10l5 cm−3). If the ionization of the background gas is dominated by photoionization due to X-rays emitted from the target (after heating by the early part of the laser pulse), then the l/r2 plasma density gradient is effective in stabilizing the growth of SRS. This stabilization leads to a substantial increase in the allowable density.