Introduction: The relationship between elevated lipoprotein (a) (Lp(a)) and poor prognosis in coronary artery disease (CAD) has been addressed for decades. However, data of mechanism of increased risk with plaque lipid burden has not been established. Hypothesis: This study aimed to investigate the association between Lp(a) and lipid burden in patients with intermediate CAD by Near Infrared Spectroscopy (NIRS). Methods: We retrospectively analyzed 128 patients with intermediate CAD who performed intravascular ultrasound (IVUS) during coronary angiography and checked Lp(a) level. The lipid core burden index (LCBI) for the 4-mm segments at the target lesion was calculated by NIRS. We divided the patients into 3 groups by calculating baseline Lp(a) tertile level. A mixed model adjusted for baseline sex, age, weight, pre-minimal luminal area, lesion length, apolipoprotein (Apo) E, Apo A1, Apo B100, total cholesterol, triglyceride, high density lipoprotein (HDL), low density lipoprotein (LDL), fasting glucose, past history, current medication including statin use was used to calculate the risk-adjusted target LCBI. Results: We enrolled 128 patients (60 years; male, 114; mean Lp(a) 21.03±20.84 mg/dl, Figure 1) and NIRS was taken in 90 patients among them. Mean and median target LCBI by NIRS were 78.4±60.3 and 62.0. Target LCBI significantly higher in the intermediate Lp(a) group than low Lp(a) group in risk-adjusted analyses (Lp(a)<9; 45.7 versus 9≤Lp(a)<19; 111.48, p =0.026, Table 1). However, between intermediate and high Lp(a) groups, there was no statistical difference (9≤Lp(a)<19; 111.48 versus 19≤Lp(a); 86.41, p =0.774). Conclusions: Elevated Lp(a) level is independently associated with increased lipid burden of target lesion in intermediate CAD, and it’s important for treatment decision. Further investigation is needed to clarify the effect of Lp(a) in various type and severity of plaque.