Backgaround: To investigate whether nitric oxide (NO) production is associated with serum lipid concentrations and body mass index (BMI), we measured serum nitrate and nitrites (NOx) concentrations, serum lipid profiles, and anthropometric parameters in 319 adolescents. Methods: Serum NOx concentrations were determined using the Griess reaction. Serum concentrations of triglyceride, total cholesterol, and low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (FTDL-C) were measured by standard enzymatic procedures. Results: Subjects with increased serum cholesterol or trialyceride concentrations exhibited remarkably high NOx levels. Total cholesterol and triglyceride averaged 161.5 +/- 27.4 and 205.9 +/- 107.8 mg/dl in males with NOx > 92.8 mumol/l (upper 20%), which were significantly above the values (132.4 +/- 17.2 and 58.1 +/- 20.3 mg/dl) in those with NOx < 15.6 mumol/1 (lower 20%). The prevalences of male adolescents with increased concentrations of cholesterol and triglyceride were significantly higher in the subjects with NOx greater than or equal to51.2 mumol/1 than in those with NOx < 51.2 mumol/1 (8.9% and 22.2% vs. 1.6% and 2.3%, p < 0.05, respectively). Correlation coefficients of serum lipid concentrations and anthropometric parameters vs. serum NOx concentrations were higher in males than in females for cholesterol (r=0.28 vs. 0.23), triglyceride (r=0.51 vs. 0.42), HDL-C (r=-0.25 vs. -0.16), and BMI (r=0.39 vs. 0.27). Conclusions: NO production is closely associated with serum lipid concentrations in adolescents, and these associations are stronger in males than in females. (C) 2004 Elsevier B.V. All rights reserved.