Aim To determine whether small, dense low density lipoprotein cholesterol （sdLDLC） affects common carotid artery intima-media thickness （CCA-IMT） or not. Methods 130 patients who had dyslipidemia, diabetes mellitus, hypertension, or smokers participated in this experiment. SdLDLC was collected from automatic analyzer, and CCA-IMT analysis datas were obtained from high-resolution B-mode ultrasound. Results The sdLDLC in CCA-IMT thickening group was significantly higher than that in CCA-IMT normal group （43.97 ± 11.35 mg/dL vs 26.01 ± 7.62 mg/dL, P＜0.001）. The positive association of CCA-IMT with sdLDLC was significant （r0.857, P＜0001）. Conclusions This result indicates that sdLDLC was the best marker of CCA-IMT and suggests that quantitative measurement of sdLDLC provides useful information for the risk assessment of CCA-IMT.