Purpose: The purpose of the study were to examine the nutritional status of severe brain injury adult patients in critical period, and to compare the nutritional states before and after tube feeding. Methods: Data from 19 patients admitted to the SICU in a university hospital due to severe brain injury were analyzed. Nutritional states were measured by anthropometric and blood biochemical indicators. Results: MAC and MAMC were significantly decreased only at 7 days after admission compared with those on the day of admission. TSF was significantly decreased from 7 days to 14 days after admission. Fat rate was significantly decreased from 3 days to 14 days after admission. Hb was significantly decreased only at 3 days after admission. Albumin was significantly decreased from 3 days to 14 days after admission. However, lymphocyte was significantly increased at 14 days after admission. TSF and Albumin became significantly worse even after initiating tube feeding. Conclusions: Nutritional status of severe brain injury patients in SICU became worse after admission whichever indicators were adopted to evaluate nutritional status, anthropometric or blood biochemical indicators, and became worse even after initiating tube feeding.