Between 1946 and 1980, enteric viruses were identified as a cause in approximately 12% of the waterborne disease outbreaks in the United States. Currently epidemiological evidence for waterborne transmission of human enteric viruses is limited to hepatitis A virus (enterovirus type 72), Norwalk virus, rotavirus, and the Snow Mountain agent. The difficulty in the isolation of many enteric viruses from clinical and water samples probably accounts for the limited number of outbreaks so far identified as causes of waterborne disease. Recently in our laboratory, we have developed a cDNA probe which is labelled with both **3**2P dATP and dCTP. It is capable of detecting as little as 1 fg of nucleic acid or 1 tissue culture infectious dose of poliovirus type 1. This is the most sensitive non-tissue culture technique ever developed for enteroviruses.