Objective: To investigate cholesterollowering effects of stauol ester (STAEST) and sterol ester (STEEST) enriched margarines as part of a lowfat diet.Design: According to a Latin square model randomized doubleblind repeated measures design with three test margarines and three periods.Setting: Outpatient clinical trial with freeliving subjects.Subjects: Thirty-four hypercholesterolaemic subjects completed the study.Interventions: Subjects consumed three rapeseed oil-based test margarines (STAEST, STEEST and control (no added stauols or sterols)) as part of a low-fat diet each for 4 weeks.Results: Mean daily intake of total plant sterols plus stauols was 2.012.04g during the two test margarine periods. In reference to control, serum total cholesterol was reduced by 9.2 and 7.3% with the STAEST and STEEST margarine, respectively (Pt0.001 for both). The respective reductions for low-density lipoprotein (LDL) cholesterol were 12.7 and 10.4% (Pt0.001). The cholesterollowering effects of the test margarines did not differ significantly. The presence of apolipoprotein E4 allele had a significant effect on LDL cholesterol response during the STAEST margarine only. Serum sitosterol and campesterol increased by 0.83 and 2.77mg/l with the STEEST (P<O.OOl), respectively and decreased by 1.18 and 2.60mg/l with the STAEST margarine (Pt0.001). Increases of serum sitostanol and campestauol were 0.11 and O.l9mg/l with the STAEST margarine (P<O.OOl), respectively. No significant changes were found in serum fatsoluble vitamin and carotenoid concentrations when related to serum total cholesterol.Conclusions: STAEST and STEEST margarines reduced significantly and equally serum total and LDL cholesterol concentrations as part of a lowfat diet.Sponsorship: Grant to the University of Kuopio by Raisio Benecol Ltd, Raisio, Finland.Descriptors: cholesterollowering diet; hypercholesterolaemic; plant sterols; plant stanols; carotenoids; vitamins; apolipoprotein E European Journal of Clinical Nutrition (2000) 54, 7157