Objectives: Biliary atresia (BA) causes neonatal cholestasis that requires hepatoportoenterostomy or liver transplantation (LT) for long-term survival. Nutritional optimization is necessary as sarcopenia and sarcopenic obesity have been associated with adverse clinical outcome. Currently, mid upper arm circumference (MUAC) is considered the most accurate indicator. The aim of the study was to determine computed tomography (CT)-based body metrics in infants with BA and to evaluate its correlation with MUAC.Methods: We retrospectively analyzed all BA infants below 2 years of age who underwent CT as part of LT screening at our hospital between 2006 and 2019. Measured variables were indexed with length and included: MUAC, total psoas muscle surface area (tPMSA), cross-sectional skeletal muscle area (CSMA), and total abdominal fat area. Intraclass correlation coefficients and Pearson coefficients were calculated. CSMA-to-abdominal fat area ratio was divided in quartiles, the lowest quartile group was considered sarcopenic obese.Results: Eighty infants with a median age of 4.6 months at LT screening were included. Intraclass correlation coefficients were: tPMSA = 0.94, CSMA = 0.92, and total abdominal fat area = 0.99. Correlation between MUAC z-score and indices of tPMSA, CSMA, and total abdominal fat area were r = 0.02, r?=?0.06, and r?=?0.43, respectively. The cut-off for sarcopenic obesity was CSMA-to-abdominal fat area ratio below 0.93.Conclusions: In BA infants, it is possible to determine CT-based body metrics during LT screening with very strong interobserver agreement. Poor correlation between CT-based body metrics and MUAC suggests that CT-based body metrics provide additional information on body composition in BA infants, such as relative muscle mass.