Purpose: The effects of three preoperative mouthwashes on salivary bacterial levels were evaluated and compared between subjects with differing periodontal status. Materials and Methods: Based on periodontal parameters, periodontally healthy individuals (n = 60) and those with gingivitis (n = 60) and periodontitis (n = 60) were randomly assigned to a single preoperative dose of chlorhexidine (CHX), essential oils (EO), cetylpyridinium chloride (CPC) or negative control mouthwashes. Saliva samples were collected between 8:00 and 11:00 a.m., before and after a single-dose rinse with the respective mouthwash. Total bacterial load and levels of Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola and Streptococcus oralis were determined by qPCR. Data were statistically analysed using paired t- and Student's t-tests (p 0.05). Results: CHX, EO and CPC showed greater antimicrobial efficacy than did the negative control. CHX [1226445.53] and EO [1743639.38] provided greater reductions in comparison to both CPC [106302.96] and negative control [37852.46]). CHX provided greater reductions of simultaneous levels of Pg [106326.00], Td [3335841] and Tf [61557.47] in the healthy group, as did EO in the diseased groups. CPC provided the greatest reduction [3775319.36] in the periodontitis group. Conclusion: Periodontal status influenced the antimicrobial efficacy of preoperative mouthwashes. Therefore, periodontal status should be taken into consideration by clinicians. The antimicrobial efficacy differed among the agents tested. CHX and EO showed the greatest efficacy. The recognition of periodontal condition by clinicians is mandatory to select the most effective preoperative mouthwash. Keywords: anti-infective agents, mouthwashes, periodontal diseases, single dose