High structural and optical quality 1.3 µm GaInNAs /GaAs quantum well (QW) samples with 42.5% indium content were successfully grown by molecular beam epitaxy. The growth of well layers was monitored by reflection high-energy electron diffraction (RHEED). Room temperature photoluminescence (PL) peak intensity of the GaIn 0.425 NAs/GaAs (6 nm / 20 nm) 3QW is higher than, and the full width at half maximum (FWHM) is comparable to, that of In 0.425 GaAs/GaAs 3QW, indicating improved optical quality due to strain compensation effects by introducing N to the high indium content InGaAs epilayer. The measured (004) X-ray rocking curve shows clear satellite peaks and Pendellösung fringes, suggesting high film uniformity and smooth interfaces. The cross sectional TEM measurements further reveal that there are no structural defects in such high indium content QWs.