Additional alpha-globin genes in sheep might produce extra alpha-globin chains and, consequently, the subject carrying triplicated (alphaalphaalpha) or quadruplicated (alphaalphaalphaalpha) haplotypes may exhibit different hematological phenotypes when compared to the normal duplicated (alphaalpha) homozygotes (NN). Both alphaalphaalpha and alphaalphaalphaalpha heterozygous (ND) and alphaalphaalpha and alphaalphaalphaalpha homozygous (DD) individuals were obtained by selection and inbreeding. Chromatographic RP-HPLC analyses of the globin chains of 65 subjects (15 DD, 20 ND and 30 NN) were performed. A highly significant linear regression (r2 = 0.967) of the alpha/beta ratio on the number of alpha-globin genes was found, and the alpha/beta ratio ranged on average from 1.0 in NN individuals to 1.2 in the ND and 1.6 in the DD subjects. Values for blood fell within the range of normality but were rather peculiar as a whole. When the erythrocytes of individuals carrying normal arrangements were compared with those of subjects with extra alpha-genes, the latter had fewer erythrocytes that were bigger in size and had a higher Hb content and a greater osmotic fragility. This hematological picture is consistent with the existence of an unbalanced alpha/beta ratio.