We report results of calculations of radiative efficiency of InxGa1-xN quantum wells embedded in wurtzite GaN epilayer. It was found that misfit dislocations with density up to similar to 10(5-6) cm(-1) could improve the quantum efficiency of the InxGa1-xN wells by more than 10 times because they reduce the quantum well built-in electric field. At higher densities, the misfit dislocations suppress the quantum efficiency of the wells since they produce an additional channel of nonradiative recombination.