Alberto P. León (1909-2001) was the Secretary of Health of Mexico beginning in 1939. He is the 1991 holder of the Mexican National Prize on Medicine and Health. Biography León was born in Irapuato, Mexico, on July 12, 1909 and died on August 4th 2001 in Mexico City. He gained his BS degree at the Preparatory School of Aguascalientes in 1926; his MD at the National University of Mexico in 1933; and MPH degree at the Harvard School of Public Health, USA in 1936. At Harvard he studied under Hans Zinsser. He was Professor of Bacteriology and Immunology at the School of Medicine, National University of México from 1946 to 1950 and since 1946 Professor of Clinics for Infections Diseases. He worked for the Department of Public Health from 1930 to 1934, doing his residency with the Medical Emergency Services of the City of Mexico during 1932 to 1933. He was Consulting Physician of the Department of Public Welfare of Mexico in 1933 and held similar post plus that of Chief of Internal Medicine of the Spanish Hospital of Mexico City from 1933 to 1934. In 1939 León was appointed General Secretary of Health in the Mexican Secretariat of Health. For his studies at the Harvard School of Public Health during 1934 to 1936, León received a Fellowship from the Rockefeller Foundation. In 1936 he became Technical Supervisor of the Department of Public Health in Mexico, after which he was Founder and Director of the Office of Epidemiology, of the same Department, from 1937 to 1940 and Founder and Director of the Institute of the BCG of Mexico from 1948 to 1965. From 1938 to 1988 he worked as a professor at the Institute for Tropical Diseases in Mexico (Instituto de Enfermedades Tropicales). In addition to his previously mentioned academic posts, he was Professor of Immunology, School of Biological Sciences, National Polytechnic Institute of Mexico, 1945 to 1950; Professor of Epidemiology, Immunology and Bacteriology, School of Public Health, 1938 to 1950; Professor, School of Medicine, University of California at Los Angeles, 1950. Leon was a leading expert on public health issues in Mexico, especially the vaccination campaign against tuberculosis. León was fellow of six national societies, President of three of them, and a member of seven international societies. From 1946 to 1949 he was President of the Mexican Society for Geography and Statistics (Sociedad Mexicana de Geografía y Estadística), the