This article summarizes different experiences from research groups working in the field of outcome research in head and neck cancer (HNC). It presents information that has been gathered over a number of years, and emphasizes areas where further research is needed. In this context, the importance of interdisciplinary and multi-institutional collaboration is emphasized. There is a substantial need for a standardized description tool to provide a common basic language for outcome research in HNC. The International Classification of Functioning, Disability and Health (ICF), as adopted by the World Health Organization (WHO), and disease-specific ICF Core Sets for HNC are introduced to describe functioning in HNC. Applications of the ICF Core Set for HNC for further research are discussed.