Recent studies have provided evidence for associations between common polymorphic markers in the coagulation factor VII (FVII) gene and plasma FVII levels. Here we describe two common, nonrelated, functional polymorphisms in the promoter region of the FVII gene, a G to T substitution at position -401 and a novel G to A substitution at position -402. Both polymorphisms strongly influence the binding properties of nuclear protein(s). The rare -401T allele is associated with a reduced basal rate of transcription of the FVII gene in human hepatoblastoma cells and with reduced plasma concentrations of total FVII (VIIag) and fully activated FVII molecules (VIIa). In contrast, the rare -402A allele confers increased transcriptional activity and is associated with increased plasma FVII levels. Together, the two polymorphisms explained 18% and 28% of the variation in VIIag and VIIa, respectively, in a group of 183 healthy, middle-aged men. It is concluded that these polymorphisms are important for the regulation of the plasma levels of FVII and that they are likely to be useful genetic markers to resolve the issue of whether a causal relationship exists between FVII levels and risk of coronary heart disease.