The radiation output power losses due to the scattering induced by spatial nonuniformities of the medium refraction index are analyzed for an active cavity of the gasdynamic laser. The analysis is based upon the nonlinear equations of chemical kinetics. The attenuation of the coherent radiation power caused by the statistically homogeneous and isotropic flow nonuniformities is treated as a passive loss measured by an extinction coefficient related to the integral scale of the turbulence and the mean‐square fluctuation of the refractive index. A set of straightforward analytical formulas are given for both the coherent and incoherent radiation power as well as for the laser efficiency.