InGaN multi-quantum-well (MQW)-structure laser diodes fabricated from III–V nitride materials were grown by metalorganic chemical vapor deposition on (111) MgAl2O4 substrates. The laser consisted of a InGaN MQW, GaN optical guiding layers and AlGaN cladding layers. The observed stimulated emission was at a wavelength around 419 nm, with a threshold current of 320 mA (13 kA/cm2) and a threshold voltage of 28 V under pulsed current injection at room temperature. The stimulated emission also showed a strong transverse electric polarization. The beam full widths at half power for the parallel and perpendicular far-field radiation patterns were 5° and 17°, respectively.