Close linkage was demonstrated between the loci governing the polymorphisms of complement component C8 alpha-gamma (C8A) and beta (C8B). Both C8 loci were linked to the chromosome 1 marker loci PGM1 and Rh. The distance between the two C8 loci and PGM1 appeared identical in males and females. A female/male ratio of 1.6 was observed between the two C8 loci and Rh. No evidence for linkage between the C8 loci and Fy was found. Preliminary results of this study were presented at the Eighth International Workshop on Human Gene Mapping, Helsinki, August 1985 (Rogde et al. 1985b).