BACKGROUND: The purpose of this study was to compare the long term effect of the cholesterol lowering diet education provided by physicians with the education provided by dieticians on serum lipid profiles of hypercholesterolemic patients. METHODS: Among 248 ambulatory patients who had mean baseline serum total cholesterol (TC) level > or = 200mg/dL and received cholesterol lowering diet education from physicians or dieticians, 41 patients who checked serum lipid profiles three times during the mean of 403 days after education were included as subjects. The differences in means of all serum lipid profiles associated with education methods after controlling for follow up duration, differences in means of all serum lipid profiles associated with follow up duration after controlling for education methods, any interaction between education methods and follow up duration on serum lipid profiles were analysed by using repeated measures of analysis of variance. The difference between the baseline lipid levels and the third lipid levels after education were analyzed by using Wilcoxon signed ranks tests in each group. Correlations between baseline serum lipid profiles and the last changes in serum lipid profiles were analyzed. RESULTS: There were no significant differences in means of all serum lipid profiles associated with education methods or follow up duration except LDL cholesterol (LDL C). The first LDL C level after education was significantly lower in the group educated by physicians compared with the baseline LDL C, but there was no such change in the group educated by dieticians. There were no interactions between education methods and follow up duration on all serum lipid profiles. The last change of total cholesterol in both groups and LDL C only in the group educated by dieticians were significant. Correlation coefficients between baseline triglyceride (TG) and change in TG, baseline LDL C and change in LDL C, baseline total cholesterol (TC) and change in TC in patients with TC > or = 240mg/dL were 0.500 (P=0.002), 0.597 (P<0.001), and 0.578 (P=0.001), respectively. CONCLUSION: The changes of serum lipid profile during more than 1 year after education were not significantly different according to diet education methods, but total cholesterol level was significantly decreased in both groups.