Laser-induced breakdown Spectroscopy (LIBS) is an analytical technique that has found its application in nuclear research due to rapid, remote, and precise analysis in hazardous environments with relatively safe methods. In fusion applications, the timely evaluation of the tritium (T) retained in the plasma-facing components (PFCs) and plasma-facing materials (PFMs) and tracking and quantifying elements such as deuterium (D), hydrogen (H), boron (B), beryllium (Be), carbon (C), and tungsten (W) and other impurities are crucial for safety purposes. Additionally, the LIBS technique is widely applied to fission fuels, including uranium (U) and thorium (Th) salts, ensuring accurate elemental analysis. The current chapter concerns LIBS applications in material monitoring, depth profile analysis, fuel retention, isotopic analysis, and Laser Ablation Molecular Isotopic Spectrometry (LAMIS), providing appropriate basics wherever necessary, and elaborating on current trends in the nuclear field.