The neonatal period is a phase of life characterized by the specifics of the anatomical structure and physiology of the organism. For this reason, with the additional factor of childbirth and related major physiological changes in the child's body, this group is accompanied by the highest incidence of pneumothorax among all the age groups. Pneumothorax is a condition of pathological accumulation of air between visceral and parietal pleura which causes partial or complete collapse of the lungs and consequently leads to respiratory failure. Pneumothorax is usually etiologically divided into several groups. Spontaneous pneumothorax can be primary or secondary, depending on whether there is pre-existing pulmonary pathology. Traumatic pneumothorax is caused by blunt or penetrating injury to the chest and lung tissue, and iatrogenic by various medical interventions. The most common signs and symptoms of pneumothorax are tachypnea, dyspnea, apnea, and cyanosis. Diagnosis is based on the clinical picture, the severity of which correlates with the size of the accumulated air volume, which is supplemented by transillumination, and is definitely confirmed by radiological methods such as X-ray and ultrasound. Treatment is individualized, depending on the severity of the clinical picture. In some cases, observation is sufficient, while others require thoracentesis and thoracic drainage, and 100% oxygen is used in therapy. In this study, conducted in the form of a short cross-sectional retrospective analysis, the data of 40 patients treated at the Department of Pediatric Surgery of the Children's Hospital Zagreb were processed. The data were collected by searching the hospital information system and the medical history archive from the period between January 2010 and October 2019. The influence of the size and thus the maturity of the child on the outcome of the pneumothorax treatment was not confirmed by statistical analysis.