Time-integrated and time-resolved photoluminescence measurements on InGaN quantum wells grown by MOCVD on two different substrates (sapphire and GaN) show that the lumi-nescence efficiency in these structures strongly depends on the intensity of carrier excitation. While at low excitation densities the recombination of excited carriers is governed by local-ization effects the behavior drastically changes at higher densities. At room temperature a suppression of nonradiative recombination could be observed that leads to an super linear increase of the luminescence.