The aim of the study was to characterize postprandial high-density lipoprotein (HDL) cholesterol metabolism in postmenopausal women and to evaluate the effect of replacement therapy with 17beta-estradiol. Sixteen healthy normolipidemic (plasma cholesterol, 5.39 +/- 0.68 mmol/L; plasma triglycerides [TGds], 1.24 +/- 0.55 mmol/L) postmenopausal women received an oral vitamin A fat tolerance test (50 g fat with 60,000 IU vitamin A/m2 body surface area). Various blood samples were taken before the test, at hourly intervals up to 8 hours, and 24 hours after ingestion of the fat load for determination of HDL cholesterol, HDL TG, and HDL apolipoprotein (apo) A-I concentrations. TG and vitamin A concentrations were also measured. A subgroup of six women were treated with 2 mg micronized 17beta-estradiol orally each day for 6 weeks, after which the oral vitamin A fat tolerance test was repeated. A reduction in plasma HDL cholesterol concentrations was observed 3 to 8 hours after ingestion of the fat load, and the minimal postprandial HDL cholesterol concentration was, on average, 31.7% (P = .04) lower than the fasting HDL cholesterol concentration. HDL cholesterol had returned to the initial value 24 hours after the fat load. The decrease in postprandial HDL cholesterol concentrations was attenuated by treatment with 17beta-estradiol. The area under the curve (AUC) for the postprandial reduction in HDL cholesterol improved substantially by 66% during 17beta-estradiol (-2.4 +/- 2.6 mmol x h x L(-1) before 17beta-estradiol and - 1.1 +/- 1.2 mmol x h x L(-1)_ during 17beta-estradiol, P = .038). In conclusion, HDL cholesterol concentrations decreased by 32% in the postprandial state in normolipidemic postmenopausal women, indicating that HDL cholesterol must be measured in the fasting state. Replacement therapy with 17beta-estradiol reduced the postprandial decrease in HDL cholesterol by 66%. This effect of 17beta-estradiol can be beneficial in reducing the risk of coronary artery disease.