Gas embolism is a severe complication of laparoscopic surgery. We report two cases: one with lethal peroperative cardiac arrest from massive coronary artery gas embolism recognized during open-chest cardiac massage; the second case, also associated with coronary artery gas embolism, resulted in severe but transient abnormal left ventricular anterior wall motion, subepicardial ischaemia and injury in ECG leads V1 to V5, but unremarkable coronary arteriography and full recovery. The pathophysiology of gas embolism occurring during a laparoscopic procedure, the mechanisms of gas entry into the systemic vascular bed, the clinical, ECG, pulse oximetry, end-tidal CO2 concentration changes and alarm signs are discussed. The diagnostic value of Doppler transoesophageal echocardiography when possible is underlined, and emergency management of gas embolism is considered.