Supragingival dental plaque is a complex polymicrobial community, with some species considered representative of a health-associated flora and others associated with diseases such as dental caries and gingivitis. Broad-spectrum antimicrobials are often prescribed to treat oral infections, which has the potential to select for resistant species and result in superinfection overgrowth. Mouthwashes containing compounds such as chlorhexidine are recommended to control or prevent plaque accumulation and oral infections. If there is concomitant broad spectrum antimicrobial treatment that selects for resistant species and if these are also chlorhexidine-resistant, it could be problematic. In this pilot study supragingival plaque from 5 individuals was aseptically harvested, suspended in sterile phosphate buffered saline and serial-diluted onto nutrient agar supplemented with 2 µg/ml chlorhexidine digluconate. Chlorhexidine-resistant species were isolated from 3 individuals. Six colonies of differing morphologies were selected and species identified by 16S rRNA gene sequencing. The identifications were Enterobacter ludwigii, Pseudomonas stutzeri, Streptococcus salivarius, Acinetobacter johnsonii, Chryseobacterium culicis and Chryseobacterium indologenes. The minimum inhibitory concentration of chlorhexidine for species growth in planktonic phase and as biofilm ranged from 2-32 µg/ml. Disc diffusion assay revealed these organisms also had resistances to at least two of the antibiotics tetracycline, erythromycin, gentamycin, kanamycin, vancomycin, chloramphenicol and ampicillin. To determine if chlorhexidine mouthwashes as supplied for use (2 mg/ml chlorhexidine) could still be of use against these organisms 3 day monospecies biofilms were exposed to mouthwash for 5-60 s, rinsed with media and allowed to grow overnight in fresh media. The optical density of the planktonic phase was then measured. No species showed planktonic growth after exposure for 30 seconds or more. Therefore, although we demonstrated that chlorhexidine and multi-antibiotic resistant bacteria were found in dental plaque, chlorhexidine mouthwashes may still prove effective in infection control.