Serum total cholesterol, high-density lipoprotein (HDL) cholesterol, triglyceride, apolipoprotein (apo) A-I and apoB concentrations were estimated and low-density lipoprotein (LDL) cholesterol levels were calculated in 132 children aged 11.4-17.3 years. The effect of feeding was investigated by estimating postprandial values and also by studying the effects of a test meal. The distribution of all data was consistent with Gaussian apart from triglycerides which was log normal. Overall fasting values were [mean (standard deviation; SD)] cholesterol 4.5 (0.8) mmol/L, HDL cholesterol 1.5 (0.4) mmol/L, LDL cholesterol 2.6 (0.8) mmol/L, apoA-I 1.5 (0.3) g/L, apoB 1.0 (0.4) g/L and triglycerides 0.76 (0.38-1.51) mmol/L, the values for triglycerides being mean (95% confidence intervals). Girls had higher triglycerides than boys [0.82 (0.43-1.54) versus 0.70 (0.36-1.33)] and different effects of age on lipids were found, HDL cholesterol being negatively correlated with age in boys (r = -0.37; P < 0.001), but not in girls, and apoA-I being negatively correlated with age in boys (r = -0.31; P = 0.006), but positively correlated with age in girls (r = 0.32; P = 0.008). Triglycerides rose and HDL cholesterol fell following feeding and inconsistent effects were seen on apoA-I and apoB.