Disinfection capacity determinations using solutions prepared from effervescent tablets of sodium dichloroisocyanurate (NaDCC) and from solutions of sodium hypochlorite (NaOCI) indicated high activity against a range of organisms, which represent adequate safety margins for disinfection. NaDCC showed significantly higher activity than NaOCl solution against all bacterial species tested but activity againstCandida albicanswas similar. Results indicate that differences in activity between NaDCC and NaOC1 formulations are not entirely due to pH effects and that fundamental differences exist between properties and mode of action of the 2 hypochlorite systems.