The Working Group of the Czech Pneumological and Phthisiological Society proposed a simple classification of post-COVID-19 patients into four originally established clinical groups. These groups (A-B-C-D) are based on the presence or absence of respiratory symptoms (dyspnea, cough, chest pain) and signs of pulmonary involvement (decreased TLco, latent respiratory insufficiency, lung impairment according to chest X-ray/HRCT) at least three months after COVID-19 diagnosis.