Background: Sarcopenia has been widely studied in solid tumors. However, its presence and prognostic significance in hematological malignancies and transplantation cases are not clear enough. Aims: In this study, we aimed to evaluate the presence of sarcopenia and its effects on transplantation success in patients undergone stem cell transplantation. Methods: Twenty-four patients who had autologous or allogenic stem cell transplantation between May 2021 and January 2022 were included in this study. Patients who had a secondary non-hematological malignancy, neuropathy or paralysis, chronic liver/kidney disease, glomerular filtration rate <60 ml/min, congestive heart failure were excluded. Patients with a body mass index (BMI) <20.0 kg/m2; 20.0 - 24.9 kg/m2; 25.0 -29.9 kg/m2; > 30 kg/m2 were considered as underweight; normal weight; overweight and obese respectively. Low muscle mass was evaluated with the Bioelectrical Impedance Analysis (BIA) method. TANITA-SC-240MA device was used to measure body composition by BIA method. The low skeletal muscle mass index (SMI) was considered as ≤10.76 kg/m2 in men and ≤ 6.76 kg/m2 in women. The muscle strength was evaluated by using a handgrip dynamometer (TAKEI 5401 Hand Dynamometer, 100 kg). The average of 3 measurements were calculated and <30 kg in men and <20 kg in women were considered as low muscle strength. Patients were evaluated by bioelectrical impedance analysis (BIA), hand grip test, sit-stand test within 1 week before administration of preparative regimens for stem cell transplantation. The neutrophil and trombocyte engraftment days, presence of bacteremia, need for thrombocyte infusion and hospitalization time were analyzed due to the presence of sarcopenia. Results: 24 patients were included in our study. The median age of the patients was 48 (23-67), and 16 patients (66%) were female. Three patients (12.5%) were 65 years or older. Two patients had autologous stem cell transplantation previously and were undergone allogeneic transplantation due to the relaps. Among all patients, 5 patients (20.8%) were obese, 5 patients (20.8%) were overweight, 9 patients were (37.5%) normal weight and 5 patients were (20.8%) underweight. 4 patients (16.6%) were determined as sarcopenic. According to the BMI values of the sarcopenic patients, 3 were underweight and 1 was obese. Muscle strength and SMI were significantly lower in patients with sarcopenia (p: 0.035; p: 0.01, respectively) (Table 1). There was no significant relationship between the presence of sarcopenia and gender, age, BMI, diagnosis, neutrophil and platelet engraftment days. Although the length of hospitalization in patients with sarcopenia seemed to be longer, it was not statistically significant (p=0.83) (Table 1). The administration of parenteral nutrition was more frequent in patients with diabetes mellitus. When the patients were evaluated in terms of mortality on the 100th day, this value was found to be 50% in the group with sarcopenia. Image:Summary/Conclusion: Sarcopenia is more common in patients who are candidates for allogenic transplantation compared to autologous transplantation. However, since the number of patients included in our study was low, the effect of sarcopenia on transplantation success could not fully clarified. Prospective studies with larger number of patients are needed on this subject.