Studies in our laboratory have previously demonstrated in hamsters a superior cholesterol-lowering ability of plant sterol (PS) esters enriched in stearate compared with linoleate. We therefore conducted a randomized, double-blind, 2-group parallel, placebo-controlled study to test the cholesterol-lowering properties of stearate-enriched PS esters in normo- and hypercholesterolemic adults. Thirty-two adults, 16 per group with equal number of males and females in each group, participated in the 4-wk study. Participants consumed 3 g/d (1 g three times per day with meals) of either PS esters or placebo delivered in capsules. Serum LDL cholesterol concentration significantly decreased 0.42 mmol/L (11%) and the LDL:HDL cholesterol ratio decreased 10% with PS ester supplementation, whereas LDL particle size and lipoprotein subclass particle concentrations (as measured by NMR) were not affected. The percent change in LDL cholesterol was positively correlated with baseline lathosterol concentration (r = 0.729; P = 0.0014), indicating an association between the magnitude of LDL change and the rate of whole-body cholesterol synthesis. Serum campesterol (but not sitosterol) concentration significantly increased in the PS ester group. Serum tocopherol, retinol, and beta-carotene concentrations were not affected by PS ester supplementation. Thus, our findings demonstrate the usefulness of a novel stearate-enriched PS ester compound in decreasing LDL cholesterol in both normo- and hypercholesterolemic adults. The extent to which PS ester fatty acid composition affects intestinal micelle formation and cholesterol absorption in humans requires further study.