An 18-month-old male patient, classified as American Society of Anesthesiologists I, with bilateral inguinal hernia was scheduled for operation. Preanesthetic evaluation revealed history of completed medical treatment of acute bronchitis 10 days ago, and his respiratory examination was recorded as normal. He was successfully operated under general anesthesia with a laryngeal mask. After removal of the laryngeal mask, he displayed signs of hypoxia. Respiratory sounds were undetectable in the left thorax. He was intubated due to failure of adequate ventilation. Positive pressure ventilation and bronchodilators were administered to provide sufficient ventilation. In his chest X-ray, total atelectasis was determined in the left lung. Pleural effusion was ruled out with thoracic ultrasonography. Diagnostic rigid bronchoscopy was performed, and in left bronchial tree, hazelnut fragments were removed. The patient's hemodynamic and respiratory parameters recovered quickly after foreign body removal, and the patient was transferred to intensive care unit. His parents were questioned for persistent respiratory symptoms and they gave information about repeating respiratory tract infections in the last 3 months. We predict that displaced foreign body in lobar bronchus due to mechanical ventilation can cause this condition.