This study evaluated the effect of disinfection time (10, 30 and 60 minutes) on the dimensional changes of stone casts poured against an irreversible hydrocolloid impression material (Jeltrate). Impressions were made of a stainless steel analog of a maxillary arch. The impressions were sprayed with bleach, iodophor, phenol, and water and were stored for designated times before poured in a type IV stone (Vel-mix). The arch width, length, and depth of the vault of the resultant casts were measured by use of a contact measuring device (MicroVal) capable of measuring to 0.0001 mm. Data were analyzed with two-way analysis of variance at the 95% confidence level. Results indicated that disinfection treatment of alginate impressions with surface disinfectants did not cause significant dimensional changes in the resultant stone casts from statistical and clinical points of view.