Laser-induced breakdown spectroscopy (LIBS) has emerged as a flexible and effective analytical tool for the elemental analysis of biological tissues, including hair and nails, to assess mineral imbalances or long-term exposure to environmental contaminants. This chapter offers a comprehensive overview of the use of LIBS in evaluating trace elements in keratinized tissues such as nails and hairs in order to study disorders and diseases. This approach is useful for determining exposure to toxic substances, establishing a disease diagnosis, and monitoring nutritional status. In contrast to conventional techniques, LIBS has a number of notable advantages, including that no sample preparation is required for a real-time, in-situ analysis, which makes it a highly effective and non-invasive method. In addition to demonstrating the capabilities of LIBS to assess the elemental profiles of these keratinized tissues, the chapter also includes a discussion of the structural composition of hair and nails by describing case studies and data from recent research, emphasizing its potential to improve clinical diagnoses and environmental monitoring.