An elevated white blood cell (WBC) count and elevated C-reactive protein (CRP) have been associated with an increased risk of adverse cardiac events. The relation between these 2 parameters of heightened systemic inflammation was characterized in patients who underwent percutaneous coronary intervention (PCI). Femoral arterial blood samples from a prospective registry of 100 patients who underwent PCI were obtained immediately before the procedure. The concentrations of CRP and interleukin-6 were determined by an enzyme-linked immunosorbent assay. Patients were stratified according to tertiles of ascending WBC counts before PCI. Univariate analysis compared patients in the highest WBC count tertile with the lower tertiles for clinical, angiographic, and procedural characteristics, as well as pre-PCI cytokine concentrations. Multiple logistic regression analysis was performed to examine the association between the elevated WBC count and baseline elevations in either CRP or interleukin-6, accounting for the simultaneous effect of confounding characteristics. Approximately 75% of patients had stable or unstable angina pectoris versus a marker-positive acute coronary syndrome. Patients in the highest WBC count tertile were more likely to be smokers, have received unfractionated heparin, have a marker-positive acute coronary syndrome, and have a CRP >3.0 mg/L. Multivariate analysis showed that only elevated troponin-I before PCI was independently associated with the highest WBC count tertile (odds ratio 10.9, 95% confidence interval 3.7 to 32.4, p < 0.01). In patients with negative troponin I findings, CRP >3.0 mg/L was a powerful independent predictor of an elevated pre-PCI WBC count (odds ratio 3.78, 95% confidence interval 1.07 to 13.3, p = 0.04). In conclusion, in patients with troponin I negative coronary syndromes, a pre-PCI elevation in the WBC count reflected cytokine-mediated inflammation.