By combining the polymerase chain reaction (PCR) of the gamma globin gene promoters with synthetic oligonucleotide analysis we have diagnosed the -196 C----T and the -117 G----A substitutions in heterozygous carriers of non deletional A gamma HPFH from two unrelated Italian families. The identification of the beta-thalassemic defect in a compound heterozygote for -196 A gamma HPFH/beta thalassemia allows us to discuss the effect of this gamma promoter mutation on the globin chain synthetic pattern, and to make a comparison with the mutation at the -117 position.