Objective: To evaluate the prevalence of contamination, minimum inhibitory concentration (MIC) of chlorhexidine against the isolated microbes and also to assess the surface activity of chlorhexidine in three commercially available alginate impression materials. Materials and Methods: Twelve sealed packets of three different routinely used alginate impression materials were used. Three 0.1 gram samples were aseptically obtained from each packet. These were inoculated in glucose broth, thioglycolate broth and sabouraud’s dextrose agar tubes and were incubated for seven days. Surface activity of chlorhexidine in alginate mix was assessed using the Agar well technique. Results: A total of 24 out of 36 samples inoculated on various media showed growth, with an average contamination frequency of 67%. Bacillus species was highest in all three brands, followed by aerobic spore bearing bacilli and coagulase negative staphylococcus. Pseudomonas species was detected in two brands. All dilutions at 20μg/ml or above were clear of turbidity at 0.02% concentration, 10μg/ml or above were clear of turbidity at 0.05% concentration and all dilutions were clear of turbidity at 0.1% concentration. Conclusion: The level of contamination with microorganisms in commercially available alginate materials is effective alternative for disinfection impression material.