Fourteen HLA‐A and 18 HLA‐B antigens were studied in three samples of Pyrenean populations: 198 unrelated individuals of a “Pays Basque” group; 212 non‐Basque individuals from a valley in Beam, l'Ouzom; and 73 non‐Basque individuals from the neighboring valley of Bareges.The results in the Basque and the non‐Basque people from l'Ouzom were comparable: the gene frequencies of HLA‐A29, Aw19.2, B17 were increased and the haplotypes HLA ‐ Aw 19.2, B18; A29, B12; A2, B5; Al, B17 were found frequently with a striking linkage disequilibrium; HLA‐B18 had an increased gene frequency in all these Pyrenean populations, while Bw35 was frequent in l'Ouzom and Bareges, but not among the Basques. The characteristics of Bareges were very different: the gene frequencies of HLA‐A2, All, B7 were increased while the frequency of HLA‐B5 was low; the most characteristic haplotypes were HLA‐A2, B12; A2, B18; All, Bw35; All, B27.It is interesting to note discrepancies between ethnic and HLA classification of the Basques and the non‐Basque population of l'Ouzom. The HLA characteristics are quite different in the Bareges sample, more closely resembli