Dry etching of III-V semiconductors under reactive ion etching, magnetron, or electron cyclotron resonance (ECR) conditions has been performed in the same reactor using the CH4/H-2/Ar plasma chemistry. The use of ECR conditions with additional RF-biasing provides the fastest etch rates, although this produces rough surface morphologies for InP. Materials such as GaAs, AlGaAs, and GaP display smooth, stoichiometric surfaces even at the highest ECR powers employed. The etching is limited by sputter-induced desorption of the etch products for all of the III-Vs investigated.