There have been many papers written about the survival of virus during exposure to disinfecting agents and most of them include, in the discussion of their results, some speculation regarding the possible influence of virus particle aggregation. This paper differs from the others. It provides direct evidence of the kind and degree of aggregation that was present among the virions that were treated with bromine as well as the PFU titers of the starters and the survivors. A dynamic system, in which disinfectant exposure time intervals as low as 0.5 seconds was developed. Polio and reovirus preparations, containing essentially all single particles, as indicated by electron microscopy, were tested in this system. The results indicated that reovirus single particle suspensions were 30 times as sensitive to bromine as poliovirus single particle suspensions, both showing essentially first order reaction kinetics with disinfection rates of 3 log base 10 per second and 6 log base 10 units per minute, respectively. Inactivation rates with slightly aggregated reovirus deviated from first order kinetics, the reaction rate declining continuously in a manner consistent with the degree of aggregation shown by electron micrographs. Temperature effects on disinfection rates using dispersed poliovirus were also investigated. The report demonstrates the effects of virus aggregation on disinfection kinetics and provides the basis for comparing the resistance of different viruses to different disinfectants under various conditions. This research can be applied to water pollution areas.