Abstract: A method and appparatus for continuously measuring the concentration of at least one component of a gas sample by means of a laser for the purpose of charging the gas sample with radiation at a frequency in the range of an absorption line of the component, and employing a detector device for receiving a measurement signal corresponding to the intensity of the transmitted radiation and an evaluation circuit. A single mode laser is employed which is linearly tuned about a gas specific absorption line by means of bandwidth modulation so that at least two different intensity measurement values are obtained for the transmitted radiation from which the extinction, and thus the concentration of the gas component, is determined.