Background: Congenital diaphragmatic hernias are common in the children. The commonest variety is the Bochdalek type of hernia. It appears through the foramen of bochdalek on the left side of diaphragm. Bochdalek hernia in adults is a rare entity. In adults hernia may occur after traumatic episode. Diaphragmatic hernia presenting as typical left pyopneumothorax with shifting of mediastinum is very rare. Case History: Our patient is a 56 year old male presented to the casualty with breathlessness, severe chest pain and decreased appetite of one week duration. He was clinically and radiologically diagnosed as left sided hydropneumothorax. Patient was in shock. Inter costal chest tube was placed on the left side. Frank pus was collected. On third day of admission food particles were collected in the water seal bag. Contrast pleuroscopy and CT thorax revealed presence of stomach in the left pleural cavity. Laparotomy was performed, which showed incarcerated and perforated stomach along with spleen inside the left pleural space. Patient improved after surgery. Conclusion: An adult patient presented with features of left pyopneumothorax. The presentation in this case was very much confusing for the physicians because there was appearance of food particles in the intercostals drainage tube. Later surgically approached and found to be incarcerated diaphragmatic hernia. Incarcerated abdominal contents were secondarily infected consequently leading to accumulation of pus in the pleural cavity.