We have typed 25 homozygous B lymphoblastoid cell lines, defined as reference panel during the Xth International Histocompatibility Workshop, using PCR (Polymerase Chain Reaction) and oligonucleotidic probes recognizing sequences of DQA and DQB genes. The polymorphism of 8 HLA-DQA1, and 12 DQB1 alleles is reported and the advantages of this technique are compared to that of other typing methods, currently used.