['The purpose of the study is to determine levels of total cholesterol (TC), low-density, and high-density lipoprotein fractions of cholesterol (LDLc and HDLc), in patients with juvenile idiopathic arthritis (JIA), and relate those to disease activity, overweight, and physical activity (PA), testing the hypothesis that the levels of cholesterol fractions are associated with inflammation as well as with overweight and low PA.', 'Two hundred ten patients with JIA were included in this descriptive cross-sectional study. TC, LDLc, HDLc were measured, and associations with clinical disease activity (JADAS27), biomarkers of inflammation (myelo-related protein complex 8/14 (MRP8/14), C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR)), body mass index (BMI), waist-to-height ratio (WtH ratio), and PA were explored.', 'Mean values for TC, LDLc, and HDLc in the patients were within the normal range for Danish Children. HDLc was negatively correlated with MRP8/14 (r\u2009=\u2009-0.343, CI -0.474 to -0.201, p\u2009<\u20090.0005) but was not related to overweight or PA. Neither TC nor LDLc showed any association with inflammation, overweight, or PA. MRP8/14 correlated positively with CRP, JADAS27 and WtH ratio (r\u2009=\u20090.277, CI 0.142 to 0.413, p\u2009=\u20090.001).'] Are lipoprotein cholesterol fractions related to markers of inflammation in children and adolescents with juvenile idiopathic arthritis : a cross sectional study?