This chapter explores the role of salivary immune and endocrine biomarkers in diagnosing and managing skin and mucocutaneous diseases. These conditions, including allergic, inflammatory, and autoimmune disorders, often present complex diagnostic and therapeutic challenges. Salivary biomarkers offer a promising alternative to traditional blood-based diagnostics, due to their non-invasive sampling method and the ability to reflect both local and systemic immune responses. Key biomarkers, such as cytokines, immunoglobulins, and stress-related hormones, have been identified in saliva and show associations with conditions such as atopic dermatitis, psoriasis, systemic lupus erythematosus, and oral lichen planus. Advancements in salivary diagnostics underscore the potential of biomarkers like IL-17, TNF-α, and cortisol for disease monitoring and personalized treatment approaches. Despite significant progress, challenges remain in standardizing these biomarkers across heterogeneous populations and in implementing cost-effective diagnostic tools into routine clinical practice. Further research is essential to validate the clinical application of these markers, develop reliable point-of-care devices, and design integrated biomarker panels that support early intervention and improve patient outcomes. The growing field of salivary proteomics and exosomal analysis heralds a transformative future for non-invasive, precision-based dermatological diagnostics.