The International Classification of Functioning, Disability and Health (ICF) is a classification designed by the World Health Organization (WHO). It has been translated and adapted to numerous languages of the world in order to make the application as wide and simple as possible. The main goal is to achieve a unique and standard language, as well as a framework for describing health and health-related conditions. MKF consists of domains, and these domains can be viewed as domains of health and domains realted to health. In physiotherapy, it is used as a statistical instrument, research instrument, clinical instrument and an educational instrument. The main characteristics of MKF are comprehensiveness, volume, classification units, organization and structure according to the mutual relationship of these elements. Cystic fibrosis is an autosomal recessive disease and is one of the most common hereditary diseases. It is a disease that affects several systems of the human body: the respiratory system, the digestive system and the reproductive system. Unfortunately, patients with this disease have a shortened life expectancy. Lenght of life is determined by the progression and severity of lung disease, which is thus the primary cause of death. In the last few decades, the life of patients has been significantly extended, due to the availability of new therapeutic interventions that affect the course of the disease. Research has shown that cystic fibrosis most often affects the population of white people. The cause of this disease is a mutation of a gene that is responsible for moving salt and water inside and outside the cells, as a result of which mucus is produced. Symptoms are present from early childhood and are different for each child. Some of the basic symptoms present in all or at least most patients are recurrent respiratory infections, caughing, wheezing, difficulty breathing and damage to the airways. Cystic fibrosis is primarily diagnosed clinically, which can be accompanied by laboratory tests. Sufferers are more likely to develop complications such as osteoporosis, diabetes, nasal polyps and sinus infections. In addition to drug therapy, which is used to treat and prevent lung problems, physiotherapy methods such as various breathing tehniques, exercises and physical activity are used to clear mucus from the respiratory tract.