He discovered reverse transcriptase in the 1970s[1] at the University of Wisconsin–Madison, for which he shared the 1975 Nobel Prize in Physiology or Medicine with Renato Dulbecco and David Baltimore.

Little, told his parents that Temin was "unquestionably the finest scientist of the fifty-seven students who have attended the program since the beginning...I can't help but feel this boy is destined to become a really great man in the field of science.

[5] Temin's parents raised their family to have values associated with social justice and independent thinking, which was evident throughout his life.

For Temin's bar mitzvah, the family donated money that would have been spent on the party to a local camp for displaced persons.

Temin was also the valedictorian of his class and he devoted his speech to relevant issues at the time including the recent hydrogen bomb activity and the news of sending a man to the moon.

[5] Temin's first exposure to experimental science was during his time at the California Institute of Technology as a graduate student in laboratory of Professor Renato Dulbecco.

As part of his doctoral thesis, Temin stated that the Rous Sarcoma Virus has "some kind of close relationship with the genome of the infected cell".

Temin's description of how tumor viruses act on the genetic material of the cell through reverse transcription was revolutionary.

This upset the widely held belief at the time of a popularized version of the "Central Dogma" of molecular biology posited by Nobel laureate Francis Crick, one of the co-discoverers of the structure of DNA (along with James Watson and Rosalind Franklin).

In 1969, Temin and a postdoctoral fellow, Satoshi Mizutani, began searching for the enzyme that was responsible for the phenomenon of viral RNA being transferred into proviral DNA.

Reverse transcriptase was also independently and simultaneously discovered in association with the murine leukemia virus by David Baltimore at the Massachusetts Institute of Technology.

After receiving the Nobel Prize from King Carl Gustav of Sweden; Temin addressed the smokers in the audience, which included the Queen of Denmark, saying he was "outraged that one major measure available to prevent much cancer, namely the cessation of smoking, had not been more widely adopted".

In 1986, Temin became a member of the Institute of Medicine (IOM)/NAS committee for national strategy for public policy issues associated with AIDS.