Atelectasis is a loss of lung volume due to the collapse of lung tissue. ARDS is the most common cause of this pathology. Due to the ventilation-perfusion discrepancy, the exchange of gases in the lungs is reduced and consequently hypoxemia occurs, which is an indication for mechanical ventilation. By short-term application of increased transpulmonary pressure, we can open a collapsed lung and this procedure is called a recruitment maneuver. There are several methods by which we achieve the opening of atelectasis.The sigh is the first mentioned RM, which is performed by raising Vt or PEEP, depending on the ventilator, during one or more breaths. The most used method is Sustained infl. which is performed by a sudden increase in air pressure in the airways over a period of time. The most commonly used is CPAP of 30-50 cm H2O for 30-44 s. Once the alveoli are opened, they are maintained as such by PEEP. Sustained infl. often has the side effects like hemodynamic changes (hypotension). Because of that, increasilgly used method is Stepwise method, which uses the gradual titration of PEEP and thus reduces excessive alveolar distension. In unilateral atelectasis, EBB is applied to prevent the adverse effects of high pressures, which are applied to recruit the atelectasis of one half of the lung, on the healthy part. One of the most recent works also shows the procedure of "targeted segmental recruitment" which was achieved with the help of a pulmonary artery catheter. The prone position has also been shown to be a good tactic to improve oxygenation and can be considered as one of the methods of RM. All methods have advantages and disadvantages, so the optimal method of RM does not exist. The patient should be approached individually and, depending on his condition,the physician should apply the method that is thought to suit him best.