The paper reports on the implementation of two-level lasing in injection microlasers with self-organized InAs/GaAs quantum dots. Emission bands related to the radiative electron-hole recombination involving ground and several  excited states of quantum dots are observed in the spontaneous electroluminescence spectra. We investigated two-level lasing via the ground and first excited states of quantum dots in microdisks with different cavity diameters. A decrease in the threshold currents is observed for both ground and first excited transitions in quantum dots with a decrease in the microdisk diameter. The temperature dependences of the threshold current density for microdisks of various diameters suggest that two-level lasing is observed up to 90–100 °C.