OBJECTIVES: The aim of this study was to determine the prevalence and prognostic implications of elevated high-sensitivity C-reactive protein (hsCRP) in patients undergoing percutaneous coronary intervention (PCI) according to body mass index (BMI). BACKGROUND: Whereas elevated hsCRP predicts adverse clinical outcome after PCI in the general population, the impact of BMI on its prognostic utility remains unclear. METHODS: Data from 14,140 patients who underwent PCI between January 2009 and June 2017 at a large tertiary care center were analyzed. Patients were divided into 4 BMI categories: normal (BMI 18.5 to <25 kg/m2, n = 2,808), overweight (BMI 25 to <30 kg/m2, n = 6,015), obese (BMI 30 to <35 kg/m2, n = 3,490), and severely obese (BMI ≥35 kg/m2, n = 1,827). Elevated hsCRP was defined as >3 mg/l. The primary endpoint of interest was the occurrence of major adverse cardiac events (MACE; defined as death, myocardial infarction, or target vessel revascularization) within 1 year after PCI. RESULTS: Elevated hsCRP was present in 18.9%, 23.6%, 33.3%, and 47.7% of the normal, overweight, obese, and severely obese groups, respectively. MACE rates were consistently higher in patients with elevated hsCRP across all BMI categories (normal, 13.4% vs. 8.3%; overweight, 11.2% vs. 7.2%; obese, 10.6% vs. 7.5%; severely obese, 11.9% vs. 6.5%; p < 0.01 for all). After multivariate adjustment, hsCRP elevation remained significantly associated with MACE independent of BMI (hazard ratios: normal, 1.43 [95% confidence interval: 1.04 to 1.95]; overweight, 1.56 [95% confidence interval: 1.21 to 1.88]; obese, 1.40 [95% confidence interval: 1.06 to 1.84]; severely obese, 1.92 [95% confidence interval: 1.35 to 2.75]; p < 0.05 for all). CONCLUSIONS: Among patients undergoing PCI, the prevalence of hsCRP elevation progressively increased with higher BMI. Measurement of hsCRP facilitates prognostic risk assessment for adverse outcome after PCI across a broad range of BMI.