Spirometry is one of the basic additional examinations which should be performed by the family doctor and other physicians of primary care. It is used to assess ventilation of the respiratory system. It measures the amount of air in the lungs and the velocity of its flow through the airways during inspiration and expiration. Reciprocal relationship between flow and volume determine whether lung function is normal or whether there are certain anomalies. Spirometry is the essential tool in diagnosis, monitoring and treatment assessment as well as establishing prognosis of numerous respiratory disorders including common lung diseases i.e. chronic obstructive pulmonary disease and bronchial asthma. Absolute contraindications to spirometry include: aneurysms of the aorta and cerebral arteries, history of retinal detachment or recent ophthalmological surgery, haemoptysis with unknown aetiology, pneumothorax (one month before) and recent myocardial infarction or recent stroke. There are no age limitations. However, the condition necessary for performing spirometry is the ability to coordinate inspiration and expiration and thus, cooperation of the patient with the health care professional who conducts the examination. A spirometer is a measuring device used to examine lung capacity and volume. It registers the amount, flow and pressure of inhaled and exhaled air in a given time. The measured air flow velocity is changed into volume. The programme, which is built in the spirometer, calculates spirometric variables and compares them with standard values. Medical practitioners use so-called basic spirometry and spirometry performed after administration of a bronchodilator, a post BD test (referred to as “a spirometry to assess the reversibility of obturation”). A correctly performed test should include at least 3 acceptable FVC measurements. Apart from this, spirometry also includes a forced expiratory manoeuvre. It consists of three subsequent phases: maximal fast inspiration, abrupt beginning of expiration and subsequent smooth and long expiration. The basic types of ventilation disorders in respiratory diseases are: obstructive and restrictive ones.