The quality of life for millions of people all over the globe has been improved by the work of diligent biologists and doctors working in the many branches of life science. An improved knowledge of how the body functions at the genetic, cellular, physiological and behavioural levels and a greater understanding of disease and pharmacology have resulted in a reduction in human suffering. The way is being paved for the effective treatment of some of the greatest health problems of the late twentieth century cancer, AIDS and diseases caused by parasites.These two volumes are collections of the Nobel Lectures delivered by the laureates, together with their biographies, portraits and the presentation speeches for the periods 1971 - 1980 and 1981 - 1990 respectively. Each Nobel Lecture is based on the work for which the laureate was awarded the prize. New biographical data of the laureate are also included. These volumes of inspiring lectures by outstanding scientists should be on the bookshelf of every keen student, teacher and professor of biological and medical sciences as well as of those in related fields.During the period 1971 - 1980 important areas of research being recognized were as diverse as hormone action and radioimmunoassays, infectious diseases, molecular genetics, immunology, computerized tomography and social behaviour. The laureates according to the specific year are:(1971) E W SUTHERLAND JR for his discoveries concerning the mechanisms of the action of hormones; (1972) G M EDELMAN & R R PORTER for their discoveries concerning the chemical structure of antibodies; (1973) K VON FRISCH, K LORENZ & N TINBERGEN for their discoveries concerning organization and elicitation of individual and social behaviour patterns; (1974) A CLAUDE, C DE DUVE & G E PALADE for their discoveries concerning the structural and functional organization of the cell; (1975) D BALTIMORE, R DULBECCO & H M TEMIN for their discoveries concerning the interaction between tumour viruses and genetic material of the cell; (1976) B S BLUMBERG & D C GAJDUSEK for their discoveries concerning new mechanisms for the origin and dissemination of infectious diseases; (1977) R GUILLEMIN & A V SCHALLY for their discoveries concerning the peptide hormone production of the brain; and R S YALOW for the development of radioimmunoassays of peptide hormones; (1978) W ARBER, D NATHANS & H O SMITH for the discovery of restriction enzymes and their application to problems of molecular genetics; (1979) A M CORMACK & G N HOUNSFIELD for the development of computer assisted tomography; (1980) B BENACERRAF, J DAUSSET & G D SNELL for their discoveries concerning genetically determined structures on the cell surface that regulate immunological reactions.