Biomarkers are commonly reported endpoints in basic and clinical research trials. However, as technical developments increase the volume and scope of biomarker data, guidance on how to implement this knowledge into daily clinical practice is required. This special topic issue aims to provide such guidance. The current and potential future impact of biomarkers in head and neck oncology, allergology, autoimmunity, imaging techniques, otology, angioedema, and sleep medicine is presented by highly respected experts in these fields. This issue will be an invaluable resource for clinicians looking to carry the latest research findings into their own clinical work-up.