Lipoprotein lipase (LPL) and apolipoprotein CIII (apoCIII) play an important role in HDL-cholesterol and triglyceride metabolism. This study examined the effects of LPL S447X and apoCIII SstI polymorphisms on the plasma lipid and lipoprotein concentrations in Vietnamese girls. Three hundred and fifty-one Vietnamese girls, from 7 to 9 y of age, were randomly selected from the urban and rural areas of Ho Chi Minh City, Vietnam. The presence of LPL S447X and apoCIII polymorphism was determined using the Invader assay, and the plasma lipid concentrations were measured by an enzymatic method. Dietary intakes and anthropometrics were assessed for each child. The frequencies of LPL 447X (11.9%) and apoCIII S2 (32.6%) polymorphisms in the Vietnamese were similar to those of other Asian populations. The frequency of LPL 447X was the same as that in Caucasians but the frequency of apoCIII S2 was approximately 3.8 times that in Caucasians. Overall, LPL 447X polymorphism was associated with a higher HDL-cholesterol concentration (7.4%, P = 0.007) and a lower triglyceride concentration (-13.6%, P = 0.04) than LPL 447S. The apoCIII S2 polymorphism was not associated with an increase in the plasma triglyceride concentration in Vietnamese girls with a low fat intake. However, due to the high frequency of the apoCIII SstI polymorphism and the increasingly westernized diet in Vietnam, attention should be paid to the interaction of genotype with the Vietnamese diet.