The frequency of HLA alleles at HLA-DR and DQ loci, and that of the related HLA-D specificities, were estimated in the Italian population. 109 healthy unrelated subjects, born in several Italian regions and living in the district of Torino, were studied. DNA typing was achieved by the restriction fragment length polymorphism (RFLP) analysis of HLA-DR beta, DQ alpha and beta genes, hybridizing specific probes with TaqI digested DNAs. The present study allowed to define in more detail the HLA class II polymorphisms in the Italian population.