The etching of gallium nitride by reactive ion etching has been investigated to determine the effect of the addition of nitrogen to boron trichloride plasmas. The etch rate and do bias are monitored while the reactor parameters are systematically varied. The experimental results indicate that the etch rate of GaN is enhanced when nitrogen is added to BCl3 plasmas. Surface analysis by x-ray photoemission spectroscopy and electron microscopy indicate that there is little etch induced damage. The etch rate of sapphire has also been studied and is found to decrease with nitrogen addition allowing the GaN/sapphire selectivity td be enhanced with added nitrogen.