This study was undertaken to determine the relative resistance of six enteroviruses to ozone by using a continuous flow, completely mixed reactor under controlled laboratory conditions. The relative resistance of these viruses to ozone was found to be, in descending order, poliovirus 2, echovirus 1, poliovirus 1, coxsackievirus B5, echovirus 5, and coxsackievirus A9. The resistance of poliovirus 2 was approximately forty times that of coxsackie A9. An increase in residual ozone concentration resulted in a decrease in resistance to inactivation. The effect of pH on viral resistance was investigated and the viruses were observed to be more resistant at low or acidic pH than at neutral pH. Experimental design and procedures are detailed. Includes 8 references, tables, figures.