Increased concern over the transmission of acquired immunodeficiency syndrome, hepatits B, herpes, and other diseases has prompted research into the disinfection of dental impressions. Among the factors to be considered when dental impressions are disinfected is the stability of the disinfectant solutions during storage and use. This study is concerned with the effect on disinfectant solutions of repeated immersion of alginate dental impressions taken in metal trays. The effects of the impression materials, metal trays, and dilution were evaluated, and the impact of light, heat, and storage were also addressed. The findings indicated that in the test solutions, although considerable chlorine was consumed during the disinfection procedures, bactericidal activity was maintained, while in the control solution both chlorine content and bactericidal activity were remarkably stable.