Haptoglobin subtypes were analysed by isoelectric focusing in four populations from Colombia, England, Nigeria, and India. There is a wide range of variation of allele frequencies in these four populations: HP*1S = 15–28%, HP*1F = 5–19%, HP*2FS = 54–79%. With the exception of the English, and the Spanish-speaking population of Colombia, all interpopulation comparisons showed significant heterogeneity. There is an extreme variation for the HP*1F allele in different populations, and a possible geographical cline of the HP*2FS allele increasing from west to east. The data presented here suggest that HP subtypes provide a useful anthropogenetic marker for racial differenti