Genes involved in inflammatory processes are candidates for predisposition to prothrombotic syndromes. The variable number of tandem repeat (VNTR) polymorphism in the P-selectin glycoprotein ligand (PSGL)-1 gene has been associated with ischemic cerebrovascular disease but not with coronary heart disease (CHD). We assessed the effect of the VNTR polymorphism on CHD in two independent case/control studies. In the first study 281 CHD patients and 397 healthy blood donors were genotyped for the VNTR alleles in PSGL-1. The prevalence of homozygous carriers of the PSGL-1 VNTR allele with 15 repeat units was significantly higher in the CHD patients (5.3% vs. 1.5%) than in controls, suggesting an effect of this marker in CHD. To validate the findings genotyping was performed in a second study including 2,578 CHD patients, 731 patients without CHD, and 1084 healthy blood donors. The larger case control study had a power of 99.9% to detect the initially observed difference but failed to confirm the putative role of PSGL-1 VNTR polymorphism in CHD. Frequencies of the PSGL-1 VNTR 15 repeats for homozygous carriers were 2.2% in healthy blood donors, 2.3% in patients without CHD and 2.7%, in CHD cases, respectively. These results demonstrate that the PSGL-1 VNTR polymorphism is not a genetic risk factor for CHD. Adequately powered studies are prerequisites to obtain reliable results about genotype-phenotype relationships of new candidate genes in complex diseases.