Description of DNA fragments associated to HLA class I gene is possible by using restriction enzymes which determine these fragments and specific DNA probes which permit their detection. In one family, with a child presenting a recombination between HLA-A and C, six fragments determined by the enzyme BglI were found to be polymorphic. The informative fragments segregate with HLA, either with a whole haplotype or with one of the two recombinant segments of the HLA complex. In a small sample of population they correlate with one (A11) or with a group of known cross-reactive antigens serologically defined (A3 and A11; A25 and A26. Another fragment is associated with unknown cross-reactive antigens (A2 and A29).