The leading role in the treatment of patients in intensive care units is mechanical ventilation. It occupies a leading position in severely ill and vitally-threatened patients. It is carried out on patients who, for whatever reason, are not able to ensure gas exchange in the body by means of their own breathing. The development of mechanical ventilation of lungs is described in the Old Testament, the oldest written document and until the present day it has come a long way from a technological point of view. Thanks to today's modern electronics, microprocessors, computer technology and new findings on ventilation, these devices are being advanced and getting closer to the real needs of patients. There are two groups of ventilation, invasive and non-invasive. The invasive group includes a tracheal intubation of the patient and connecting the patient to a device (respirator), the non-invasive can be performed with a negative and a positive pressure in the breathing space. The modern mechanical ventilation started with a non-invasive ventilation of patients with a negative pressure (iron lungs), and much later the devices for application of the invasive ventilation were developed. Mechanical ventilation is tasked to ensure adequate gas exchange in the lungs, to apply precise oxygen concentration, to maintain the expansion of the lungs, maintain alveolar ventilation and help the patient in reducing energy consumption during breathing. Before the start of ventilation it is important to determine the parameters for the patient and they depend on gender, height, clinical condition such as acute respiratory distress syndrome (ARDS), hypercapnia, COPD, neurotrauma. It takes high knowledge and expertise of the staff who handles the appliances to know how to determine the parameters, identify and prevent complications. Lately, the interest in non-invasive methods (oronasal masks, nasal masks, full face mask or helmet) has increased, because it provides comfort and is painless for the patients.