Lasing in microdisks with an asymmetric waveguide formed by selective oxidation was achieved under optical pumping in the temperature range 5–180 K. InGaAs quantum dots (QDs) formed by submonolayer deposition were used as the active region. The experimentally determined quality factor Q of a microdisk cavity is no less than 104. The temperature shift of the resonance mode wavelength is attributed to the dispersion and the temperature dependence of the effective refractive index of a microdisk. The observed temperature dependence of the lasing threshold is related to thermal excitation of carriers from QDs into GaAs.