This paper aims to outline briefly the main stages of Frederick Sanger's scientific activity -the only person to have won two Nobel Prizes in Chemistry (1958, 1980). His work on the structure of proteins, especially that of insulin, and the determination of base sequences in nucleic acids made an immense impact on the development of biochemistry and especially on the development of a new scientific field -molecular biology. His methods for determining the primary structure of proteins and nucleic acids helped biochemists and molecular biologists to determine the structure of many proteins and nucleic acids and laid the basis for genetic engineering.