In this second note on AIDS, clinical aspects and epidemiology of the disease are reviewed so as to complete what has already been said in the first note which was concerned with etiology and pathogenesis. Publications that have appeared so far are reviewed not only as far as the classification of the different superinfections due to the state of immunodeficiency is concerned but also with a view to the clinical course of its various stages, i.e. the impairment of the organs involved, from the internistic point of view as well as from that of different branches of medicine, including oncology. Finally, a statistical picture of epidemiology in Italy and in different regions of the country is presented with special attention to different epidemiological patterns and to the age groups involved. The third note, to be published, will be concerned with diagnostic, therapeutic, and above all preventive measures.