White blood cell (WBC) count has been shown as a risk factor for cardiovascular disease. Decreased insulin sensitivity has been suggested as the link between these two entities. Our aim was to study the potential relation between insulin sensitivity and WBC count in patients with coronary artery disease. In order to assess insulin sensitivity, we performed 83 insulin suppression tests before and after therapy in 50 patients with coronary artery disease. Patients with glucose intolerance, arterial hypertension or obesity were excluded. Steady-state plasma glucose (SSPG) and insulin sensitivity index (ISI=1 000 x glucose infusion rate/SSPG) were considered as a measure of insulin sensitivity. WBC count, blood platelets, fibrinogen, microalbuminuria, creatinine, urea and HbA1c were also assessed. Simple and multiple correlation analysis were carried out between insulin sensitivity parameters and the other variables measured. There were significant correlation between SSPG and WBC count (r=0,32: p=0,003) and microalbuminuria (r=0,28: p=0,012). We also found statistically significant correlation between ISI and WBC count (r=0,27: p=0,015) and microalbuminuria (r=0,24: p=0,029). No correlation could be detected between either SSPG or ISI and the other variables measured. In multiple regression analysis, WBC count was found to be an independent predictor of both SSPG (p<0.01) and ISI (p<0.05). Our data show the existence of a significant relationship between decreased insulin sensitivity and WBC count in patients with coronary artery disease. The results of this study suggest that an elevated WBC count could be postulated as part of the insulin resistant syndrome.