The optoacoustic method has by now an almost one-centurY-long history of appl ication in spectroscopy, but it was only with the advent of the laser that it became a convenient and effective method among the vast family of spectroscopy techniques. The great variety of these techniques is capable of tackling most diversified tasks, such as the achievement of a high sensitiv ity and a high spectral or temporal resolution. The optoacoustic method is one of the simplest and most versatile ways to attain a high sensitivity for both gaseous and condensed media. It is precisely for this reason that the method has found wide use, and that we have decided to publish a mono graph reviewing the information on this method available in the literature and gathered by us at the Institute of Spectroscopy during the past few years. We hope that such a systematic exposition of the material scattered throughout numerous scientific journals will be of use to many potential readers. The reader will undoubtedly notice the absence in our monograph of references to some recent works, but unfortunately, this is inevitable when the translation and publication of a book in a foreign language takes sev eral years. Nevertheless, we tried our best to cover the entire field from the material available to us, but unfortunately, some recent publications might be missing due to the time lag for the translation and publication in a language foreign to us.