Purpose: The aim of the present study was to investigate the effect of using two disinfectant solutions for both polyether and addition silicone impression materials on the surface roughness and surface hardness of type IV dental stone die material. Materials and Methods: two types of elastomeric impression materials (addition silicone and polyether) and two types of disinfectant solutions 2% chlorhexidine and 5.25% sodium hypochlorite were used. A total of 30 impressions divided into two groups (15 for each impression material). Each group was subdivided according to the disinfectant application into three subgroups (n=5): subgroup N not subjected to any disinfection (control), subgroup C subjected to 2% chlorohexidine gluconate and subgroup S subjected to 5.25% sodium hypochlorite. Disinfection time was 10 minutes. All impressions were poured with type IV dental stone die material. The surface roughness was determined by 3D Surface Roughness Measurement Using a Light Sectioning Vision System, while surface hardness was determined using Vickers Micro-hardness Tester. Data were collected and statistically analyzed. Results: For polyether groups the results showed significant difference in surface hardness between the control group and the two experimental groups. For addition silicone groups the results showed presence of significant difference of the control group with sodium hypochlorite group. The results also showed no significant difference in surface roughness for all tested groups. Conclusion: The Surface hardness of the tested stone cast is adversely affected by disinfection with sodium hypochlorite. The surface roughness of the tested stone cast was not influenced by the disinfectant solutions. Impression material used in the present study has no effect on surface roughness (Ra) and surface hardness of the stone cast.