The goals of the present publication are (a) to identify standardised methods and tools applied in clinical trials and cohort studies to assess key functional aspects in HNC, using the Brief ICF Core Set for head and neck cancer (ICF-HNC) as a reference and (b) to propose a set of sound standardised methods and tools suitable to assess functional problems in HNC. This work contributed to the development of practical ICF-HNC based guidelines targeting the standardised measurement of functional outcomes in HNC follow-up and clinical research in Germany. A systematic review of randomised and clinical controlled trials, and observational studies in HNC were carried out to identify standardised methods and tools. Suitable methods and tools were then selected based on pre-defined criteria. 210 assessment methods and tools were identified in 136 studies: 146 patients reported outcomes (PRO) and 64 tools rated by health professionals. Altogether 59 tools were considered suitable to be included in guidelines: four side effects classifications, two performance status scales, 31 PROs, 10 assessment criteria for clinical examinations, seven assessment methods and tools for the evaluation of technical, equipment-based procedures and five technical, equipment-based procedures. It was possible to identify and select sound and standardised assessment methods and tools for almost all functioning areas defined in the ICF-HNC. Since no tool sufficiently covers support provision by immediate family and by health professionals as well as economic self-sufficiency, we recommend a corresponding update of existing tools.