Hydropneumopericardium is defined as the presence of air and water in the pericardial cavity. Several causes have been postulated which can lead to hydropneumopericardium including trauma, infections secondary to gas-producing bacilli, fistula formation, positive pressure ventilation or even spontaneously without an underlying cause in healthy adults and rarely after pericardiocentesis. We report an uncommon instance of hydropneumopericardium after pericardiocentesis in a 35-year-old man, which developed due to a leaky drainage system. It was immediately drained through the subxiphoid approach under echocardiographic guidance, and the patient was relieved. Hydropneumopericardium is an uncommon but easily diagnosable and avoidable complication of pericardiocentesis. It should be suspected whenever the patient develops increasing dyspnoea following a temporary relief by pericardiocentesis.