OBJECTIVE To determine abnormalities of cholesterol metabolism in children with acute rheumatic fever (ARF). METHODS Cross-sectional study and prospective study. METHODS Pediatric ward of the Khon Kaen (Thailand) University Hospital. METHODS Forty-six confirmed patients with ARF (during the acute and recovery phases of disease), 51 siblings, and 92 age- and sex-matched control children. METHODS None. RESULTS Serum samples of these children were studied for serum total cholesterol, high-density lipoprotein cholesterol, and triglyceride levels and liver function tests. No significant differences were found in mean serum total cholesterol levels (3.68 +/- 0.86 mmol/L [142.4 +/- 33.3 mg/dL] vs 3.75 +/- 0.67 mmol/L [145.0 +/- 25.8 mg/dL], 3.79 +/- 0.75 mmol/L [146.4 +/- 29.0 mg/dL], and 3.80 +/- 0.59 mmol/L [146.9 +/- 23.0 mg/dL]) or mean triglyceride levels (1.19 +/- 0.33 mmol/L vs 1.16 +/- 0.51, 1.12 +/- 0.37, and 1.07 +/- 0.41 mmol/L) (during ARF vs after ARF, sibling, and age- and sex-matched control children, respectively). The children with ARF had significantly lower mean levels of high-density lipoprotein cholesterol and of albumin than did the other groups (analysis of variance, P < .0001). In the ARF group, high-density lipoprotein cholesterol and albumin levels varied inversely with the clinical severity of carditis, while, in contrast, triglyceride and alkaline phosphatase levels varied with the clinical severity of carditis. CONCLUSIONS This study confirms abnormalities of cholesterol metabolism in ARF. Hepatic dysfunction associated with the clinically detectable severity of carditis or inflammation might explain the observed differences in serum high-density lipoprotein cholesterol and triglyceride levels in these children.