The fluorescence of molecular iodine isotopes 129 I and 127 I excited by Kr- and Nd-lasers was studied. A laser fluorescence method for determining the concentration of iodine-129 in gaseous media in real time was proposed. The sensitivity of this method makes it possible to carry out reliable and prompt control of the technological process of irradiated nuclear fuel reprocessing at nuclear fuel cycle enterprises and ecological monitoring of the atmospheric air. The promising nature of the lidar (remote) method for detecting these isotopes in the atmosphere is shown.