Radioimmunoassay (RIA) is a technique in which researchers use radioactive isotopes as traceable tags to quantify specific biochemical substances from blood samples. Rosalyn Yalow and Solomon Berson developed the method in the 1950s while working at the Bronx Veterans Administration (VA) Hospital in New York City, New York. RIA requires small samples of blood, yet it is extremely sensitive to minute quantities of biological molecules within the sample. The use of RIA improved the accuracy of many kinds of medical diagnoses, and it influenced hormone and immune research around the world. Before the RIA was developed, other methods that detected or measured small concentrations of biochemical substances required large samples of blood-- often too large for researchers to collect. With the development of RIA, researchers could use a single drop of blood to detect and measure the concentration of some biochemical substances. By 1970 doctors used RIA to measure follicle stimulating and luteinizing hormones to diagnose and treat infertility in women. Further developments led to neonatal screening programs for hypothyroidism.

Muriel Wheldale Onslow studied flowers in England with genetic and biochemical techniques in the early twentieth century. Working with geneticist William Bateson, Onslow used Mendelian principles and biochemical analysis together to understand the inheritance of flower colors at the beginning of the twentieth century. Onslow's study of snapdragons, or Antirrhinum majus, resulted in her description of epistasis, a phenomenon in which the phenotypic effect of one gene is influenced by one or more other genes. She discovered several biochemicals related to color formation. Onslow's methodology also partly contributed to the establishment of the field of chemical genetics.

George Herbert Hitchings researched and developed medications that targeted specific parts of DNA replication processes to treat cancers and various illnesses in the US during the twentieth century. By studying DNA analogs, or manmade substances that resemble the structure of naturally occurring DNA components and are capable of inhibiting DNA replication, Hitchings promoted a novel approach to pharmaceutical research and drug development, known as rational drug design. Using that novel approach, Hitchings and his research team created acyclovir, one of the first medications to effectively treat herpes, a condition that can be sexually transmitted but can also be passed from mother to child, causing life-threatening illness in infants. Hitchings also contributed to the development of cancer treatments, immunosuppressant medications, anti-viral medications, and anti-malarial medications. Hitchings’s research on DNA analogs established rational drug design as a method to create new pharmaceutical drugs, some of which treat sexually transmitted illnesses.