The effects of eight disinfectants commonly used in dental practice on the vital physical properties of a fully set die stone were examined. Distilled water was used as a control. The properties used to evaluate tile effects of the disinfectants were detail reproduction, surface hardness, bulk strength, dimensional accuracy, and chemical interaction. Some of the disinfectant solutions where found to be reactive and to alter the properties of the stone to various degrees. However, two of the agents where less reactive and caused little or no observable change in the physical properties of the stone.