Nonselective dry etching of GaN, In0.12Ga0.88N, and their multiquantum wells (MQW) was examined using a Cl-2/CH4/H-2/Ar plasma at room temperature. The etching characteristics were studied as functions of CH4 concentration, inductively coupled plasma power, and radio frequency table power. Nonselective etching of MQW using a Cl-2/CH4/H-2/Ar plasma was monitored by means of laser interferometric reflectance. Ga, In, and GaCl as well as CN were observed as group III and group V etch products, respectively, in the optical emission spectrum during plasma etching. By optimizing the CH4 concentration in the gas mixture, the roughness on the etched surface and the sidewall of the MQW could be substantially reduced. These results indicate that Cl-2/CH4/H-2/Ar plasma chemistry, combined with a postannealing process for etch-damage recovery, is suitable for the fabrication of optoelectronic devices using GaN, InGaN, and GaN/InGaN MQW.