The frequencies of three polymorphisms in the promoter region of the human protein C gene (C/T at -1654, A/G at -1641 and A/T at -1476) have been determined. All three polymorphisms show allelic frequencies of about 0.60 and 0.40. The determination of the frequencies of the haplotypes of these polymorphisms showed that three of them (CGT, TAA and CAA) account for 88% of the observed haplotypes.