Globin chain synthesis, RNA and DNA of beta-thalassemic patients from Azerbaidzhan were analyzed. A beta-mRNA deficiency was found in beta +-thalassemic reticulocytes. In one case of beta +-thalassemia, it was possible to study nuclear and cytoplasmic RNA from spleen erythroid cells. The alpha/beta mRNAs sequence ratio was 5 in the nuclear and cytoplasmic RNAs. In patients with beta o-thalassemia a different level of beta-globin mRNA was demonstrated. Gene mapping analysis indicated that the general organization of the beta-globin gene was normal in the investigated cases of beta-thalassemia.