Stress ulcers or stress-related mucosal disease (SRMD) is defined as "acute superficial inflammation lesions of the gastric mucosa induced when an individual is subject to abnormally elevated physiologic demands."[1] Studies have shown that SRMD occurred in 75%-100% ICU patients[1]. Gastrointestinal bleeding due to SRMD is an important complication in critically ill patients. The frequency of clinically important bleeding ranged from 5.3% to 33%.[2] The mortality in ICU patients with stress related bleeding approaches 50%, which is much higher than the patients without bleeding (9%). [3] In 1999, the American Society of Health-System Pharmacists (ASHP) published guidelines on the use of stress ulcer prophylaxis in medical, surgical, respiratory, and pediatric ICU patients [2]. PPIs and H2RA are widely used in China current clinical practice for the prevention of stress ulcer bleeding. However, there is no epidemiology data to show the risk factors for stress ulcer bleeding and the bleeding rate of Chinese neurosurgical critically ill patients who are usually suffering from brain trauma, cerebral haemorrhage or brain tumour operation. Information is needed to know about the characteristics in Chinese critically ill neurosurgical patients.