We report the fabrication and the characterization of low‐loss, single‐mode GaAs/AlGaAs ridge waveguides. The waveguides were grown by organometallic vapor phase epitaxy and were characterized at 1.52 &mgr;m wavelength. Their propagation losses were evaluated by measuring the finesse of the Fabry–Perot waveguide resonators formed by cleaving two opposite ends of these waveguides. Losses as low as 0.15 dB/cm were measured for single‐mode waveguides, which is the lowest value reported to date for single‐mode semiconductor waveguides. Such low‐loss waveguides should be useful in guided‐wave components for integrated optoelectronics.