The antimicrobial efficacy and anti-adhesive attributes of a proprietary denture cleanser were evaluated. To determine cleanser antimicrobial efficacy, Streptococcus mutans was grown on denture acrylic strips which were then exposed to the cleanser. To evaluate anti-adhesive efficacy, the strips were treated with the cleanser and then placed in the Strep. mutans suspension. Following incubation, adhered bacteria were removed and enumerated by viable counting. Treated denture acrylic plates were also placed in a parallel-plate flow chamber and then exposed to Strep. oralis. Images of adhered bacteria were analysed to determine biofilm coverage. Biofilm removal force was quantified by increasing the flow rate between the acrylic plates. The cleanser exhibited a 100% kill against Strep. mutans adhered to the acrylic surface, and inhibited attachment of cells by 66%. The flow chamber study found that cleanser-treated denture acrylic allowed the formation of a multilayer biofilm which was easily removed by a slight increase in flow rate.