Background: Stridor is a high-pitched sound that occurs as a result of turbulent airflow due to upper airway obstruction. The most common cause of chronic stridor in children are congenital anomalies of the respiratory tract.

Objective: To identify the etiology of chronic stridor in children based on flexible bronchoscopy findings.

Methods: This retrospective study included all patients treated due to chronic stridor at the Pulmonology department of the Mother and Child Healthcare Institute of Serbia from January 2013 to December 2022. The data were obtained from patients? medical history. The flexible bronchoscopy was performed according to standardized protocol.

Results: During the ten-year period, the stridor was registered in 188 patients. The most common cause of chronic stridor was laryngomalacia (41.1%), type I being the most frequent, followed by airway vascular compression (11.9%) and subglottic stenosis (9.4%). Among patients with laryngomalacia, 68.6% had gastroesophageal reflux. Dysphagia was present in 31.2% of participants and negatively correlated with nutritional status (p< 0.001). In the case of comorbid conditions (GER, congenital heart disease, achalasia, neurological impairment) or associated anomalies, conservative or surgical treatment was performed. No severe complications have occurred in any patient during bronchoscopy.

Conclusion: Laryngomalacia is the most common cause of stridor in children. The most important procedure for determining the etiology of stridor is flexible bronchoscopy, which should be done in every child with chronic stridor.