Identification of HLA-DR, DQ and DP alleles at the DNA level is an important tool for bone marrow transplantation (BMT). We recently encountered an aplastic anemia patient for whom the ability of molecular HLA typing to utilize alternative sources of DNA proved to be fundamental for her treatment. After repeated failures to obtain HLA typing using peripheral blood, HLA-DR and DQ alleles were identified by molecular techniques utilizing two hairs as a source of DNA, ultimately resulting in successful BMT from a sibling donor. This case clearly illustrates the potential of DNA methodologies for HLA typing in patients whose condition precludes the use of more traditional methods.