The essay reconstructs the antithalassemia campaign carried out by means of population screening and pre-marriage counseling for about twenty years in Italy, immediately after the relationship between microcythemia and Cooley's anemia had been established, as well as its genetic bases. We examine the Italian contributions to the understanding of the genetics and of the clinical treatment of thalassemic disorders, and analyze the approaches to prevention as well as the results obtained by the first campaign against a genetic disease, conceived and largely implemented in Italy by Ezio Silvestroni and Ida Bianco. We discuss the resistances met by the antithalassemia campaign due to the cultural and organizational backwardness of the Italian medical community and of the public health system. Moreover we analyze the explanations and interpretations of the problematic results of these experiences in terms of morbidity reduction. It will be pointed out that the objective of genetic counselling practised in that context assumed the concept of disease prevention at the population level, and it was far from the idea, emerged in the 1970s, of non directive genetic counselling.