['Obesity is associated with metabolic derangement and non-alcoholic fatty liver disease (NAFLD). Macrophages are involved in liver inflammation and fibrosis, and soluble (s)CD163 is a macrophage activation marker.', 'To associate sCD163 with parameters of paediatric obesity and NAFLD, as well as changes in these parameters during lifestyle intervention.', 'We studied 117 obese children during a 10-week lifestyle intervention; 71 completed the 12-month follow-up. We recorded clinical and biochemical data, and performed liver ultrasonography.', 'Baseline sCD163 was higher in children with elevated alanine transaminase (ALT) (2.3\u2009±\u20090.7 vs. 2.0\u2009±\u20090.6\u2009mg\u2009L(-1), P\u2009=\u20090.03), steatosis (2.3\u2009±\u20090.7 vs. 2.0\u2009±\u20090.6\u2009mg\u2009L(-1), P\u2009=\u20090.01) and high paediatric NAFLD fibrosis index (2.3\u2009±\u20090.7 vs. 1.9\u2009±\u20090.6\u2009mg\u2009L(-1) , P\u2009=\u20090.03). Baseline sCD163 was independently associated with ALT, cholesterol and high-sensitivity C-reactive protein (hs-CRP). The change in sCD163 during lifestyle intervention was associated with changes in ALT, homeostatic model assessment of insulin resistance (HOMA-IR), hs-CRP and cholesterol, and inversely associated with the change in high-density lipoprotein cholesterol.'] Is the macrophage activation marker sCD163 associated with changes in NAFLD and metabolic profile during lifestyle intervention in obese children?