Background. Hydropneumothorax is a disorder characterized by the presence of free fluid and air in the pleural cavity. This case is very rare in children and mostly is a complication of pneumonia with bronchopleural fistulas.
Objective. To report a case of hydropneumothorax in patient with Community Acquired Pneumonia and Sepsis in a a-one-month-and-fourteen-days-aged boy. 
Case. A-one-month-and-fourteen-days-aged boy was admitted with shortness of breath since 2 days before admission. There was history of coughing with no mucus since 3 days before admission. There was no history of cyanosis, feve, and seizure. He was admitted to C Hospital for 3 weeks with abscess on face and it was drained. Physical examination revealed: RR was 68/minutes, SpO2 97%(with NRM); HR was 162/minutes, temperature was 37oC. Thoracic examination revealed there was retraction and decreased of breathing sound on the left hemithorax, and rales on the right hemithorax. Laboratory findings revealed: hemoglobin level 11.8 gr / dl; leukocyte 34,860 / mm3, platelet 275,000 / mm3, 92% of granulocytes, 5.8% of lymphocytes. Abcess culture (previous hospital): Serratia plymuthica, blood and pleural culture : Staphylococcus aureus (Methicilin resistent Staphylococcus aureus). Chest radiograph: bilateral pneumonia, left pleural effusion. CT scan of thorax revealed left hydropneumothorax, right pneumonia, and bilateral atelectasis. He was treated with water seal drainage (WSD) and antibiotics.
Conclusion. A case of hydropneumothorax, CAP, and sepsis in a-one-month-and-fourteen-day-aged boy was reported. The diagnosis was based on history taking, physical examination, laboratory and radiologic examination findings. The prognosis was dubia.