Objective <p>The International Classification of Functioning, Disability and Health (ICF) provides a biopsychosocial framework for describing patients’ functioning, but its comprehensive structure poses challenges for routine clinical use and health system reporting. In Poland, rehabilitation services lacked a standardized approach to functioning assessment that would support coordinated care and comparable outcome documentation at national level. This paper aims to describe the development and implementation of a tool for the quality assessment of therapeutic rehabilitation in Poland, focusing on the standardisation of patient functioning assessment using the International Classification of Functioning, Disability, and Health (ICF).</p> Design <p>The study was structured around the creation of functioning assessment standards (categorical profiles), a unified system for planning patient support (intervention sheet), and post-rehabilitation assessment sheets to ensure comprehensive evaluation of rehabilitation effectiveness at individual, hospital, and national levels.</p> Methods <p>Within a national implementation project, we developed an ICF‑based functioning assessment system for inpatient and outpatient rehabilitation, including categorical profiles for major rehabilitation types, auxiliary tools (Short Intuitive Descriptions, rating guides, conversion protocols) and a dedicated IT application. The system was pilot‑tested in 12 rehabilitation centres (1 800 patients; 1 200 inpatients and 600 outpatients) using pre‑ and post‑rehabilitation assessments and WHO’s WHODAS 2.0 questionnaires.</p> Results <p>The pilot indicated that ICF‑based categorical profiles were feasible to use in routine practice and sensitive to changes in patients’ functioning over the course of rehabilitation. The system differentiated outcomes between centres and showed moderate to high inter‑rater agreement for most ICF categories, with several codes reaching very high ICC values, which require cautious interpretation. WHODAS 2.0 scores were broadly consistent with ICF‑based profiles, particularly in activity and participation domains. Conclusion: This pilot suggests that an ICF‑based functioning assessment system can support more standardized, biopsychosocially oriented rehabilitation in Poland, while highlighting important implementation challenges, including resource demands, staff training needs and difficulties in assessing environmental factors. Further research is needed to establish long‑term outcomes, refine psychometric properties and evaluate cost‑effectiveness of system‑wide implementation.</p>