The reactive ion etching of AlInGaP and GaAs with a gas mixture of SiCl4, CH4, and Ar is examined. Process parameters such as gas flow composition and radio-frequency power input are varied. The CH4 flow variation in particular has a substantial effect on the morphology of AlInGaP, while generally the effects on GaAs are less dramatic. The etch rates of AlInGaP and GaAs show similar trends. A suitable etching process was found and applied to an AlInGaP/InGaP index-guided 675 nm laser structure.