Both genetic and environmental factors influence the variation in von Willebrand factor (VWF) levels between individuals, the main genetic variable known to be involved in differences in VWF levels being the ABO blood group. The -1185A/G polymorphism in the 5'-regulatory region of VWF gene has been associated with plasma VWF levels in a normal population. The objective of our study was to examine the relationship between the -1185A/G polymorphism and plasma VWF levels in a total of 420 individuals from two Brazilian ethnic groups. The -1185A/G genotypes were identified using polymerase chain reaction (PCR) amplification of the 864-bp VWF promoter region followed by AccII restriction digestion. Allele and genotype frequencies were significantly different between Afro-Brazilians and Euro-Brazilians. The -1185A allele frequency was 62% in Afro-Brazilians and 41% in Euro-Brazilians. Although Afro-Brazilians had higher plasma VWF levels than Euro-Brazilians, the ethnic differences were not significant. No association was observed between -1185A/G genotypes and VWF plasma levels in either ethnic groups. The present data indicate that there are no ethnic differences in VWF levels. The -1185A/G polymorphism showed significantly different frequencies between Afro-Brazilians and Euro-Brazilians, but in our study, it did not appear to play a role in the determination of VWF levels.