The invention relates to methods for generating radiation at resonance transitions of metal atoms in mixtures of inert gases and metal vapors that are excited by an arc electric discharge. The technical effect of the claimed invention is raising the efficacy and service life of radiation sources at metal atom resonance transitions, which are excited by a low-pressure arc discharge. The technical effect is achieved due to that, according to a method for generating radiation at resonance transitions of metal atoms in mixtures of inert gases and metal vapors, which method includes exciting mixtures of inert gases and metal vapors by a high-frequency alternating longitudinal electric discharge, a discharge is excited by essentially rectangular current pulses with an off-duty ratio not more than 2.0 and duration not exceeding the efficient life-time of resonance state of the radiating metal atom.