['n-3 Fatty acids lower plasma triacylglycerols not only in the fasting state but also in the postprandial state. However, it is not known whether chylomicrons, chylomicron remnants, and VLDLs are all affected equally or whether some lipoprotein species are lowered preferentially.', 'Lipoproteins, including large and small chylomicron remnants, were determined specifically with the aid of a newly developed method involving a combination of size-exclusion chromatography and fluorometric determination of retinyl palmitate, which served as a marker for exogenous fat.', 'Twelve hypertriacylglycerolemic men were treated for 6 wk with 4 capsules containing 85% fish-oil concentrate/d; each capsule contained 850 mg n-3 fatty acid ethyl esters (49.1% eicosapentaenoic acid by wt and 32.2% docosahexaenoic acid by wt). Oral-fat-tolerance tests were performed before and after the treatment. Blood samples were drawn in the fasting state and until 8 h postprandially.', 'Treatment with n-3 fatty acids reduced the fasting VLDL-triacylglycerol concentration by 44% (P < 0.05) and postprandial chylomicrons and VLDLs at 4, 6, and 8 h (P < 0.05) by 49-64% and 36-43%, respectively. Chylomicron remnants were reduced only in the late postprandial phase: large chylomicron remnants by 19% at 6 h and by 43% at 8 h (P < 0.05) and small chylomicron remnants by 31% at 8 h (P < 0.05).'] Are postprandial chylomicrons and VLDLs in severe hypertriacylglycerolemia lowered more effectively than are chylomicron remnants after treatment with n-3 fatty acids?