It is not known in detail whether postprandial lipaemia is associated with coronary artery disease (CAD) in women. To investigate this, we administered an oral vitamin A/squalene/fat meal to 24 post-menopausal women with angiographically proven CAD who were not taking hormone replacement therapy, and to 30 healthy controls (18 without and 12 with hormone replacement therapy) to evaluate the effects of CAD on postprandial lipoprotein metabolism. This was done by assessing squalene, triacylglycerols, retinyl palmitate and apolipoprotein B-48 (apoB-48) during the subsequent 24 h. The subjects with CAD had significantly higher fasting concentrations of squalene and apoB-48 in triacylglycerol-rich lipoproteins (TGRL) compared with the controls. The postprandial areas under the incremental curve of TGRL apoB-48, chylomicrons, very-low-density lipoprotein (VLDL) and TGRL squalene, and of retinyl palmitate in VLDL only, were significantly higher in women with CAD than in controls. Adjustment for fasting values did not eliminate the differences in postprandial squalene and apoB-48 between CAD and controls. The postprandial responses of control subjects were not influenced by hormone replacement therapy. The peaks of squalene and retinyl palmitate of the controls, but not of the women with CAD, occurred significantly earlier (P<0.01 for both) in chylomicrons than in VLDL. The findings suggest that lipoproteins that accumulate postprandially are labelled by dietary squalene, and that these lipoproteins may be atherogenic in post-menopausal women.