This in vivo study aimed to compare and evaluate the effectiveness of three different disinfectants on irreversible hydrocolloid impressions by immersion method. A total of 30 patients were included in the study, and three irreversible hydrocolloid impressions were obtained from each patient. The impressions were divided into three groups, and each group was treated with a different disinfectant solution. The disinfectants used in the study were 2% glutaraldehyde, 0.525% sodium hypochlorite, and 1% sodium hypochlorite. The impressions were immersed in their respective disinfectant solutions for 10 minutes, followed by rinsing with distilled water and air-drying. The impressions were then evaluated for surface roughness, dimensional accuracy, and detail reproduction. The results showed that all three disinfectants had a significant effect on the surface roughness of the impressions. Glutaraldehyde had the most adverse effect on the surface roughness, followed by 1% sodium hypochlorite and 0.525% sodium hypochlorite. The dimensional accuracy and detail reproduction of the impressions were not significantly affected by any of the disinfectants. Based on the results of this study, it can be concluded that 0.525% sodium hypochlorite is the most suitable disinfectant for irreversible hydrocolloid impressions. It is effective in disinfecting the impressions without significantly affecting their dimensional accuracy and detail reproduction. However, further research is needed to determine the long-term effects of disinfection on irreversible hydrocolloid impressions.