Experimentally, high-carbohydrate diets have been shown to elevate trigtycerides, but it has not been established whether this rise is permanent or transient. The authors approached this question by studying 719 boys from worldwide populations with marked differences in long-term carbohydrate intake. Fasting serum triglycendes, total cholesterol and high density lipoprotein (HDL) cholesterol concentrations were measured in boys aged 8 and 9 years from 12 countries-eight in Europe, three in Africa, and one in Asia. A standardized protocol was used for obtaining tasting blood and for the preparation, storage and transport of serum, and all measurements were made in one laboratory. Published values were used for the United States. Mean values for lipid levels per country were compared with the percentage of daily energy intake consumed as carbohydrate or fat, as determined by survey. Boys from populations with higher carbohydrate and lower fat intake had lower low density lipoprotein (LDL) cholesterol levels (univariate regression coefficient (± standard error, -0.028 ± 0.009 mmol/liter for each percent of energy from carbohydrate; p < 0.01, n = 13), but they also had higher fasting triglycerides (0.010 ± 0.002 mmol/liter for each percent ofenergy from carbohydrate; p < 0.01, n = 13) and lower HDL cholesterol levels (-0.022 ± 0.003 mmol/liter for each percent of energy from carbohydrate; p < 0.001, n = 13). These trends agree with results from epidemiologic studies within populations and from controlled dietary trials, and suggest that in normolipidemic healthy subjects, high-carbohydrate, low-fat diets cause higher triglyceride levels than diets that are higher in fats and oils. © 1990 by The Johns Hopkins University School of Hygiene and Public Health.