HLA class II antigens and DRB1, DQA1, DQB1 alleles were studied in 16 Italian and in 16 Sardinian patients with pemphigus vulgaris (PV). In the last group the complete HLA A-DQ haplotypes, including the complotypes, were defined by family studies. As in other populations, two PV susceptibility haplotypes were found: HLA-DRB1*0402, DQA1*0301, DQB1*0302 and HLA-DRB1*1401, DQA1*0104, DQB1*0503. The first haplotype was largely prevalent in the Sardinian patients and was a part of the extended haplotype HLA-A2, Cw4, B35, S31, DR4, DQ8. The strength of the allele associations to PV is in agreement with the view that the main PV susceptibility genes are the DRB1*0402 and DQB1*0503 alleles. A genetic resistance to PV seems to be conferred by the HLA-DR3, DQ2 haplotype in the Sardinian population.