The advent of recombinant DNA techniques has resulted in the detection of a large number of polymorphic marker loci many of which are not useful for linkage studies because of their low degree of polymorphism. However, when no apparent recombination exists between several closely linked markers, the amount of 'information' available can be significantly increased by establishing haplotypes from those loci; that is, haplotyping increases the number of heterozygotes at marker loci. Haplotyping can be problematic when more than one of the loci involved in the haplotyping are heterozygous and the phase of the haplotypes cannot be inferred from the data. We present a method for recoding the phenotypic marker data for pedigree members that will circumvent this difficulty.