The selectivity for etching the binary (GaN, AlN, and InN) and ternary nitrides (InGaN and InAlN) relative to each other in Cl-2/Ar, CH4/H-2/Ar, ICI/Ar, or IBr/Ar electron cyclotron resonance (ECR) plasmas, and Cl-2/Ar or CH4/H-2/Ar reactive ion (RIE) plasmas was investigated. Cl-based etches appear to be the best choice for maximizing the selectivity of GaN over the other nitrides. GaN/AlN and GaN/InGaN etch rate ratios of similar to 10 were achieved at low RF power in Cl-2/Ar under ECR and RIE conditions, respectively GaN/InN selectivity of 10 was found in ICI under ECR conditions. A relatively high selectivity (>6) of InN/GaN was achieved in CH4/H-2/Ar under ECR conditions at low RF powers (50 W). Since the high bond strengths of the nitrides require either high ion energies or densities to achieve practical etch rates it is difficult to achieve high selectivities.