Indiana University-Purdue University Indianapolis (IUPUI) / Objective: Nutritional assessment and diagnosis of malnutrition in pediatric patients is dependent on anthropometric measurements. In macrocephalic children, current anthropometric measures may fail to correctly diagnose malnutrition. The purpose of this study is to determine if the measurement of mid-upper arm circumference (MUAC) in pediatric patients with macrocephaly better identifies children at nutritional risk as compared to weight-for-length (WFL) or body mass index (BMI). Methods: A cross-sectional pilot study of children aged 6-36 months with a head circumference 2 SD above the mean was performed. Visual assessment was used as the clinical “gold standard” for presence of malnutrition. MUAC was compared to the WFL or BMI for each child to determine which anthropometric measurement better identified presence of malnutrition. Statistics: Two-way contingency tables were used to summarize the relationships between each pair of assessments of whether a child is malnourished. Agreement between the methods was evaluated using kappa statistics and percent agreement. Analyses were performed using SAS version 9.4 ™ statistical software. Results: Twenty patients were included who met study criteria. The mean head circumference z-score was 2.6. The mean BMI/WFL z-score was 0.9, which would qualify the child as “nourished.” Of the 20 children included in the study, 20% (n=4) appeared visually malnourished on physical exam. BMI/WFL confirmed diagnosis of malnutrition in 75% (n=3) of children. MUAC confirmed diagnosis of malnutrition in 75% (n=3) of children. Diagnosis of malnutrition using BMI/WFL as compared to visual assessment had a non-significant p-value of 0.317. Diagnosis of malnutrition using MUAC as compared to visual assessment had a non-significant p-value of 0.317. With a p-value of >0.5, there is no statistically significant difference between BMI/WFL and MUAC in diagnosis of malnutrition. Conclusion: MUAC did not perform better than BMI/WFL at identifying malnutrition in pediatric macrocephalic patients.