BACKGROUND Serum small dense low-density lipoprotein cholesterol (sdLDL-C) and lipoprotein(a) [Lp(a)] levels are related to coronary disease, but their specific associations with coronary arteriostenosis in Takayasu arteritis (TA) have not been ascertained. This study explored the correlations between serum sdLDL-C and Lp(a) levels and coronary arteriostenosis in TA patients as well as the degree of artery stenosis. METHODS This retrospective study included 190 TA patients and 154 healthy subjects. TA patients were divided into three categories based on the degree of coronary stenosis: Group I, stenosis >50%; Group II, stenosis 1%-50%; and Group III, stenosis 0%. Independent risk factors for coronary arteriostenosis in TA were identified by logistic regression, followed by receiver operating characteristic curve analysis to determine the specificity and sensitivity of risk factors and Youden's Index score calculation to determine the cutoff points. RESULTS Takayasu arteritis patients had significantly higher serum levels of sdLDL-C and Lp(a) than healthy controls (p < 0.0001). The total cholesterol, triglyceride, LDL-C, sdLDL-C, and Lp(a) levels and the sdLDL-C/LDL-C ratio in Group I were significantly higher than those in Groups II and III (p < 0.05). An elevated serum sdLDL-C level elevated the risk of coronary arteriostenosis by 5-fold (cutoff value, 0.605 mmol/l). An increased serum Lp(a) level increased the risk of coronary arteriostenosis by 3.9-fold (cutoff value, 0.045 g/l). An elevated sdLDL-C/LDL-C ratio increased the risk of coronary arteriostenosis by 2.1-fold (cutoff value, 0.258). CONCLUSIONS Serum sdLDL-C and Lp(a) levels and sdLDL-C/LDL-C ratio may be used as diagnostic factors for coronary arteriostenosis in TA patients.