Photoluminescence microscopy (PLM) and photoluminescence (PL) spectroscopy have been used to investigate the influences of the number of quantum wells (QWs) and nitrogen concentration [N] on the quality of InGaAsN multiple QWs (MQWs). No misfit dislocations and/or carrier localization were observed in as‐grown InGaAsN MQWs. PL measurement results suggest that the PL efficiency and interfaces in the InGaAsN/GaAs QWs do not deteriorate with increasing number of QWs. In an InGaAsN 7 QW structure, even after annealing at temperatures as high as 850 °C, misfit dislocations were still not observed. This is contrary to the lattice relaxation behaviour of annealed InGaAs MQWs and is attributed to the impurity pinning of dislocations by nitrogen. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)