OBJECTIVE To evaluate the intercatheter reproducibility of catheter-based intracoronary near-infrared spectroscopy (NIRS) for the detection of coronary lipid core plaques (LCPs). BACKGROUND The intercatheter in vivo reproducibility of coronary NIRS findings has not been evaluated. METHODS NIRS assessment using an automated pullback catheter was performed in triplicates in 10 patients using two different NIRS catheters to evaluate the reproducibility of the lipid core burden index (LCBI). RESULTS Mean age was 62 ± 7 years, and all patients were men with high prevalence of hypertension (90%), hyperlipidemia (90%), diabetes (50%), and current smoking (50%). The mean LCBI measured by the first and second catheters was 64 ± 55 and 69 ± 47, respectively (intraclass correlation coefficient, 0.97; 95% confidence interval, 0.90-0.99; and Spearman's ρ, 0.95; P < 0.001 for both). The mean LCBI measured again with the second catheter was 71 ± 63 (intraclass correlation coefficient, 0.96; 95% confidence interval, 0.84-0.99; and Spearman's ρ, 0.95; P < 0.001 for both). The mean number of LCPs detected by the first and second catheters was 1.9 ± 1.2 and 2.0 ± 1.5, respectively (intraclass correlation coefficient, 0.75, P = 0.005 and Spearman's ρ, 0.74, P = 0.01). The mean number of LCPs at reimaging with the second catheter was 2.0 ± 1.76 (intraclass correlation coefficient, 0.96 and Spearman's ρ, 0.98; P < 0.001 for both). CONCLUSIONS NIRS measurements of LCP with two different catheters have high reproducibility. The findings support the use of NIRS to assess the status of LCP in patients over time and to assess LCP changes in response to novel treatments.