Glutaraldehyde and hypochlorite solutions have been shown to be effective disinfectants for use in the dental surgery. However, their use in the disinfecting of alginate hydrocolloid impression materials must be open to question since these materials are dimensionally unstable when immersed in aqueous solutions for any length of time. This project investigated the dimensional changes noted in casts poured into alginate impressions which had been stored for up to 60 minutes in either hypochlorite or glutaraldehyde solutions. All changes measured were considered to be within clinical tolerance.