Aims: To investigate the effectiveness of Activon® Manuka honey (Advancis Medical) in inhibiting the in vitro formation of clinically important Gram positive bacteria biofilms. Methods: Biofilms of meticillin-sensitive Staphylococcus aureus (MSSA), meticillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecalis (VRE) were cultivated in microtitre plates with and without varying concentrations of Activon for specific intervals. The extent of biofilm biomass was estimated by staining with crystal violet. Results: Concentrations of Activon above 10% (w/v) interfered with the formation of biofilms in all of the test organisms. Inhibition of established biofilms by Activon Manuka honey was dependent on concentration and time. Conclusions: Biofilms of MSSA, MRSA and VRE can be prevented and inhibited in vitro with concentrations of Activon Manuka honey that could be used in clinical practice. The efficacy of Activon Manuka honey in inhibiting biofilms in vivo must be tested. Conflict of interest: This study was sponsored by Advancis Medical, Nottingham, UK.