Diet has been linked to cardiovascular disease risk by its influence on low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and blood pressure (BP). Recent evidence suggests that vitamin C may play a role in regulation of cholesterol and BP. The cross-sectional relationships of plasma ascorbic acid (PAA) with cholesterol and BP are described in three Boston area samples: 1) 249 males and 447 females (aged 60-100 years), 2) 100 Chinese-American males and 159 Chinese-American females (aged 60-96 years), and 3) 225 male and 192 female participants (aged 20-60 years) in a randomized field trial of vitamin C supplementation. Results indicate 3.7-9.5% higher levels of HDL-C, 4.1% lower levels of LDL-C, and 1.9-5.5% lower levels of BP with each 30 mumol/L increment in PAA. These relationships may be stronger at lower levels of PAA.