Objective: To investigate the nutritional status of patients before and after hematopoietic stem cell transplantation(HSCT), and explore optimal methods for assessing nutritional status in patients with hematological diseases.Methods: This cohort study enrolled 170 patients who were diagnosed with hematological diseases and underwent allogeneic HSCT in the Department of Hematology, Peking University People’s Hospital between May2011 and April 2013. We used fixed-point continuous sampling and four nutritional screening tools, Nutritional Risk Screening 2002(NRS-2002), Mini Nutritional Assessment(MNA), Subjective Global Assessment(SGA) and Malnutrition Universal Screening Tools(MUST), in combination with body measurements, to extensively screen and evaluate nutritional risks and status in patients receiving HSCT before entering and after leaving laminar air flow rooms.Results: After HSCT, patients had significant reduction in weight, hip circumference, waist-hip ratio, calf circumference, mid-upper arm circumference, and suprailiac skinfold thickness compared with pre-HSCT measurements. Before HSCT, NRS-2002 identified that 21.2% of patients were at nutritional risks, compared with100% after HSCT. MUST indicated that before HSCT, 11.77% of patients were at high nutritional risk,compared with 59.63% after HSCT. MNA assessed that 0.06% of patients were malnourished before HSCT,compared with 19.27% after HSCT. SGA identified that before HSCT, 1.76% of patients had mild to severe malnutrition, which increased to 83.3% after HSCT. There is a significant increase in the nutritional risk and malnutrition in patients who received HSCT.Conclusions: Before HSCT, some patients already had nutritional risk or nutritional deficiencies, and prompt and close nutritional screening or assessment should be performed. The nutritional status of patients after HSCT was generally deteriorated compared with that before transplantation. Body measurements should be taken more frequently during the subsequent treatment window in the laminar air flow rooms. After HSCT, it is recommended to combine MNA and SGA to fully evaluate the nutritional status, and thus provide timely and reasonable nutritional support. Objective: To investigate the nutritional status of patients before and after hematopoietic stem cell transplantation (HSCT), and explore optimal methods for assessing nutritional status in patients with hematological diseases. Methods: This cohort study enrolled 170 patients who were diagnosed with hematological diseases and underwent Allogeneic HSCT in the Department of Hematology, Peking University People’s Hospital between May 2011 and April 2013. We used fixed-point continuous sampling and four nutritional screening tools, Nutritional Risk Screening 2002 (NRS-2002), Mini Nutritional Assessment (MNA), Subjective Global Assessment (SGA) and Malnutrition Universal Screening Tools (MUST), in combination with body measurements, to extensively screen and evaluate nutritional risks and status in patients receiving HSCT before entering and after leaving laminar air flow rooms. Results: After HSCT, patients had significant reduction in weight, hip circumference, waist-hip ratio, calf circumference Before HSCT, NRS-2002 identified that 21.2% of patients were at nutritional risks, compared with 100% after HSCT. MUST indicated that before HSCT, 11.77% of patients were at high nutritional risk, compared with 59.63% after HSCT. MNA assessed that 0.06% of patients were malnourished before HSCT, compared with 19.27% ​​after HSCT. SGA identified that before HSCT, 1.76% of patients had mild to severe malnutrition, which increased to 83.3% after HSCT. There is a significant increase in the nutritional risk and malnutrition in patients who received HSCT.Conclusions: Before HSCT, some patients already had nutritional risk or nutritional deficiencies, and prompt and close nutritional screening or assessment should be performed The nutritional status of patients after HSCT was generally deteriorated compared with that before transplantation. Body measurements should be taken more frequently during the subsequent treatment window in the laminar air flow rooms. After HSCT, it is recommended to combine MNA and SGA to fully evaluate the nutritional status, and thus provide timely and reasonable nutritional support.