Idiopathic hypereosinophilic syndrome (HES) is a heterogeneous disorder characterized by hypereosinophilia and organ damage which affects men more commonly than women (9∶1). The disease can be detected incidentally, but more often presents either insidiously or acutely with cardiac, neurological, cutaneous, pulmonary or gastro-intestinal manifestations, with cardiac involvement being a major cause of morbidity and morality in patients. 1,2 Although a major mechanism of tissue damage in HES is due to thromboembolism,3 full-blown disseminated intravascular coagulation (DIC) is apparently rare. This paper describes a man who presented acutely with life-threatening DIC complicating HES and its management, the first Chinese case reported in the literature. CASE REPORT A 62-year-old gentleman with history of hypertension followed up in the primary care clinic was admitted into the medical ward with left leg swelling, haemoptysis and exertional dyspnoea for four days. There was no chest pain or fever. On admission, he was not in respiratory distress. Blood pressure was 140/80 mmHg. The left calf was swollen with a circumference of 40 cm versus 36 cm on the right side. There were crepitations at the left lung base. Idiopathic hypereosinophilic syndrome (HES) is a heterogeneous disorder characterized by hypereosinophilia and organ damage which affects men more commonly than women (9: 1). The disease can be detected incidentally, but more often presents either insidiously or acutely with cardiac, neurological, cutaneous , pulmonary or gastro-intestinal manifestations, with cardiac involvement being a major cause of morbidity and morality in patients. 1,2 Although a major mechanism of tissue damage in HES is due to thromboembolism, 3 full-blown disseminated intravascular coagulation (DIC This paper describes a man who presented acutely with life-threatening DIC complicating HES and its management, the first Chinese case reported in the literature. CASE REPORT A 62-year-old gentleman with history of hypertension followed up in the the primary care clinic was admitted into the medical ward with left leg swelling, haemoptysis and exertional dyspnoea for four days. On admission, he was not in respiratory distress. Blood pressure was 140/80 mmHg. The left calf was swollen with a circumference of 40 cm versus 36 cm on the right side. There were crepitations at the left lung base .