Nanoparticles are used in the clinic as contrast agents, drug carriers, or theranostic agents gathering imaging and therapy purposes. They are generally developed to overcome some limitations of available active molecules, including inadequate stability, lack of specific targeting, undesired toxicity, poor water solubility, or inappropriate distribution profile. The administration routes of nanoparticles are varied, including the conventional oral and systemic routes, but local and topical administrations also occur. Hence, their complete characterization is necessarily performed in animals before reaching the clinic, similar to any drug or contrast agent. This investigation requires tracking the nanoparticle or its metabolites once administered to an animal. In this chapter, an overview of the possibilities is presented, which are offered by LIBS elemental imaging for such preclinical investigations.