Phytosterols (PS) are recommended to reduce LDL-cholesterol. However, the influence of cholesterol and fat intake on the lipid-lowering effect of PS in mildly hypercholesterolaemia is unclear. Thus, the aim of the present study was to evaluate whether the efficacy of PS is related to the composition of saturated fat and dietary cholesterol intake. Additionally, serum carotenoid content was analysed to evaluate to what extent it was undermined by PS. This was a 3-month randomised, parallel trial with a three-arm design. Patients were divided into three groups: healthy diet (n 24), healthy diet+PS (n 31) and free diet+PS (n 29), receiving 2 g/d of PS. Healthy and free diets were characterised by a daily ingestion of 6·8 % of saturated fat and 194·4 mg of cholesterol and 12·7 % of saturated fat and 268·1 mg of cholesterol, respectively. After PS therapy, patients receiving the healthy diet+PS or a free diet+PS exhibited a similar reduction in total cholesterol (6·7 and 5·5 %), LDL-cholesterol (9·6 and 7·0 %), non-HDL-cholesterol (12·2 and 8·9 %) and apo B-100/apo A-I ratio (11·5 and 11·6 %), respectively. In patients following the healthy diet, (β-carotene concentration rose by 26·9 %, whereas the β-carotene and lycopene levels dropped by 21·0 and 22·8 % in the group receiving the free diet+PS, respectively. No change was observed in carotenoid levels in healthy diet+PS group. In conclusion, the efficacy of PS in relation to lipoprotein profile is not influenced by saturated fat or dietary cholesterol intake, which confirms the positive effect of healthy diet therapy in improving the negative effects that PS exert on carotenoid levels.