HLA antigens (27 HLA alleles of the A and B loci) were determined in 20 subjects of the same family, covering three generations; 6 of them were suffering from hereditary hemorrhagic telangiectasia. The haplotype HLA A2, Bw17 was found in all the sufferers. The same haplotype was not found in clinically healthy members except two of the generation III, but a visceral angiomatosis without clinical evidence cannot be excluded. An association of hereditary hemorrhagic telangiectasia with the haplotype HLA A2, Bw17 can be suspected in this family.