We have demonstrated a novel downstream plasma activated vapor phase etching of III-V compound semiconductors using ethylene di bromide as the etchant. Highly reproducible surfaces and etch rates were obtained by monitoring the reaction process with a mass spectrometer. Etch rates on InP of up to 4500Å/min, at temperatures as low as 160°C, at an rf power input of 25 watts were achieved with no evident damage to the surface as indicated by PL measurements. Apparent activation energy measurements seem to suggest that the etch products might be organometallic in nature, in contrast to inorganic etch products seen in most etching studies. Etching is partially anisotropic and resulted in smoother surfaces when H2 was used as the carrier gas for the etchant instead of N2.