Racoons rarely get cancer. Can you imagine the surprise of scientists when, during March 2010-May 2012, 10 racoons in California and Oregon suddenly developed brain tumors? Everything suggested that the unexpected “epidemics” had an infectious origin. In fact, racoon polyomavirus was found in the tumor tissue of all affected animals, but not in 20 unaffected animals. This is not only about racoons: viruses can be the etiologic agents of many human cancers as well. The case of racoons has probably something to teach us.