Background Heme-oxygenase 1 (HO-1) is a rate-limiting enzyme in the degradation of heme to bilirubin, ferritin and carbon monoxide (CO) and may have significant anti-inflammatory function.The HO-1 gene promoter region shows microsatellite polymorphism with different (GT)n repeats, reported to differently induce gene expression, with the short allele associated with higher gene expression.We measured the acute inflammatory response using coronary artery bypass surgery (CABG) as a well-characterized and uniform stimulus and examined the correlation between levels of IL-6, C-reactive protein (CRP) and fibrinogen and their relationship to HO-1 genotype.Methods Two hundred and seventy-five consecutive patients undergoing CABG were genotyped for the HO-1 promoter polymorphism using PCR and automated DNA capillary sequencer.IL-6, CRP and fibrinogen were measured at baseline and 6, 24, 48, 72, 96 and 120 hours after CABG.Results Complete IL-6,CRP and fibrinogen measures were available in 220 patients.Before surgery IL-6 levels showed a strong correlation with CRP and fibrinogen (r=0.48, P