We present a case of diaphragmatic fibrillation (with a frequency of 600/min) in a patient at the early post-operative stages. In view of the decreased oxygen saturation and confusion, the patient was sedated and mechanically ventilated. His declining physical condition was partially associated with diaphragmatic fibrillation superimposed on heart failure and lung disease. The transthoracic echocardiography was technically difficult. Consequently, transoesophageal echocardiography was undertaken. This is the first case report presenting diaphragmatic fibrillation as an incidental finding on transoesophageal echocardiography.