—Hepatic lipase is involved in the metabolism of several lipoproteins and has a key role in reverse cholesterol transport. A common C-to-T substitution at position −514 of the hepatic lipase promoter has been associated with variations in plasma high density lipoprotein cholesterol (HDL-C) levels and hepatic lipase activity. The aim of the current study was to investigate the association of this polymorphism to lipoprotein levels in a population-based sample of 1314 male and 1353 female Framingham Offspring Study participants. In men and women, carriers of the −514T allele had higher HDL-C and apolipoprotein A-I (apoAI) concentrations compared with noncarriers. The higher HDL-C levels associated with the −514T allele was due to an increase in the HDL₂-C subfraction, and this association was stronger in women compared with men (P=0.0043 versus 0.0517). To gain further understanding about the metabolic basis of these effects, HDL and low density lipoprotein (LDL) subclass profiles were measured by using automated nuclear magnetic resonance spectroscopy and gradient gel electrophoresis, respectively. The association of the −514T allele with higher HDL-C levels seen in men and women was primarily due to significant increases in the large HDL subfractions (size range 8.8 to 13.0 nm). In contrast, there was no relationship between the hepatic lipase polymorphism at position −514 and the LDL particle size distribution after adjustment for familial relationships, age, body mass index, smoking, alcohol intake, use of β-blockers, apoE genotype, and menopausal status and estrogen therapy in women. Moreover, multiple regression analyses suggested that the C−514T polymorphism contributed significantly to the variability of HDL particle size in men and women (P<0.04). Thus, our results show that the C−514T polymorphism in the hepatic lipase gene is associated with significant variations in the lipoprotein profile in men and women.