In this case report, we describe a rare case of spontaneous diaphragmatic hernia with perforation of the incarcerated ascending colon and subsequent formation of tension pneumothorax. A 73-year-old male with a past medical history of chronic right pleural effusion, restrictive ventilatory impairment and hypertension presented to us for evaluation of severe right chest pain of few days' duration and severe dyspnoea. The chest radiograph revealed the presence of a loop of bowel in the basal right hemithorax with associated air/fluid levels. A CT scan of the chest confirmed the hydropneumothorax and revealed a right lower lobe ipo-expansion and a flogistic lung consolidation. After surgery, the patient underwent a contrast-enhanced CT scan of the chest, which showed no abnormal findings.