The HLA-A, B and DR phenotypes of 109 unrelated Tunisian individuals have been determined. The HLA-A and B antigen frequencies were compared with data reported for European Caucasoids and various Arab populations. Most similarities in antigen frequencies were seen between Tunisians and Kabyles from North Africa. A high frequency of HLA-A23 and HLA-Bw50 was observed in Tunisians and all Arab populations. A very close similarity in HLA-DR antigen frequencies exists between Tunisians and European Caucasoids. Linkage disequilibria between alleles of HLA loci were examined; many instances of previously reported antigen associations were seen in Tunisians, together with a number of associations which have not been described elsewhere. Aw34B8 and A2DRw14 are suggested as being common haplotypes in Tunisians.