This article concerns itself with the reception of Rous' 1911 discovery of what later came to be known as the Rous Sarcoma Virus (RSV). Rous made his discovery at the Rockefeller Institute for Medical Research which had been primarily established to conduct research into infectious diseases. Rous' chance discovery of a chicken tumor led him to a series of conjectures about cancer causation and about whether cancer could have an extrinsic cause. Rous' finding was received with some scepticism by the scientific community that held that cancer was not infectious and favored explanations which located the origins of cancer in the inner mechanism of the cell. After 4 years of unsuccessful effort to isolate and further determine the virus Rous felt compelled to discontinue his work on cancer viruses. When 55 years later, the significance of Rous's discovery was attested by the award of the Nobel Prize, it opened up debates about the issues of delayed recognition and scientific reputation. This article also considers why Rous' hypothesis of a viral origin of cancer could not be incorporated into the existing body of knowledge about cancer before the 1950s.