This study assessed inflammation in phenylketonuria (PKU) to examine associations with body composition, plasma phenylalanine (phe), diet, and bone health. Blood from 20 fasted females ages 11‐52 with PKU was analyzed for plasma phe, inflammation [C‐reactive protein (CRP)], and bone turnover markers (CTx and P1NP). Dual energy x‐ray absorptiometry measured body composition, bone mineral density (BMD), and content (BMC). Three‐day food records were analyzed by NDSR to calculate energy, carbohydrate, fat, total protein and phe intake. Spearman’s coefficients assessed correlations between CRP (non‐normal) and all parameters. Nine (45%) were overweight or obese (BMI >25). CRP was elevated (>1mg/dL) in 33.3% and correlated with BMI (r‐square=0.49; p‐value=0.03) and marginally with % body fat (r‐square=0.34; p‐value=0.14). CRP was not associated with plasma phe, nutrients, BMD or BMC. CRP was inversely correlated with PINP, marker of bone formation (r‐square=‐0.47; p‐value=0.04) and marginally with CTx, marker of bone resorption (r‐square=‐0.40; p‐value=0.09). Preliminary data indicate 1 in 3 females with PKU had elevated CRP indicating inflammation. Inflammation was related to high BMI, low bone turnover and potentially with high fat mass, but not plasma phe or diet. Risk of chronic conditions or bone health issues secondary to chronic inflammation warrants investigation in PKU.Grant Funding Source: Supported by the National Center for Advancing Translational Sciences of the NIH