The purpose of this study was to evaluate the influence of human saliva on the antimicrobial effect of a tissue conditioner containing an antibiotic agent, silver-zeolite. Samples of each tissue conditioner with or without silver-zeolite were prepared and a plastic disk was used as a control. Candida albicans and nosocomial respiratory infection-causing bacteria, Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Pseudomonas aeruginosa and the Streptococcus milleri group (S. constellatus and S. intermedius), were selected as test microorganisms. Antimicrobial effects of samples after water or saliva immersion for 28 days were evaluated by counting the number of viable cells [colony forming unit (CFU)] in each microbial suspension (100 microL). All data were statistically analysed by one-way anova and Bonferroni's test (P < 0.05). The antimicrobial effects of samples with silver-zeolite immersed in saliva against C. albicans, S. aureus and MRSA were observed while CFU of P. aeruginosa indicated no significant difference from that of the control. As for the S. milleri group, its CFU after saliva immersion showed the significantly smaller value than that of the control. It is concluded that the antimicrobial effects of samples containing silver-zeolite against all tested microbes except for P. aeruginosa and the S. milleri group are not influenced by saliva immersion for 28 days.