Objective: Dental caries is a common oral infection prevalent in developing countries. Streptococcus mutans, a commensal bacterium of the oral cavity, plays a major role in the etiology of caries and root canal infection. Sodium hypochlorite and Chlorhexidine are used in the prevention of caries and as root canal medicament though they cannot be used in combination. Study Design: Different concentrations of passion fruit pulp extract were evaluated to measure the most effective way against Streptococcus mutans. For this bacterial inhibition zones were measured for each concentration in millimeter and compared. Results: The most effective concentration of passion fruit pulp extract was 40% to 45% against Streptococcus mutans. Conclusion: The present study aimed to evaluate alternative, inexpensive, good in taste, simple and effective method for sanitization of tooth cavity as well as root canal system. The antimicrobial efficacy of passion fruit pulp extract as irrigant and cavity disinfectant is evaluated and compared with the standard irrigant sodium hypochlorite.