AIMS: To evaluate the anti-biofilm activity of the commercially available essential oils from two Boswellia species. METHODS AND RESULTS: The susceptibility of staphylococcal and Candida albicans biofilms was determined by methyltiazotetrazolium (MTT) staining. At concentrations ranging from 217.3 microg ml(-1) (25% v/v) to 6.8 microg ml(-1) (0.75% v/v), the essential oil of Boswellia papyrifera showed considerable activity against both Staphylococcus epidermidis DSM 3269 and Staphylococcus aureus ATCC 29213 biofilms. The anti-microbial efficacy of this oil against S. epidermidis RP62A biofilms was also tested using live/dead staining in combination with fluorescence microscopy, and we observed that the essential oil of B. papyrifera showed an evident anti-biofilm effect and a prevention of adhesion at sub-MIC concentrations. Boswellia rivae essential oil was very active against preformed C. albicans ATCC 10231 biofilms and inhibited the formation of C. albicans biofilms at a sub-MIC concentration. CONCLUSIONS: Essential oils of Boswellia spp. could effectively inhibit the growth of biofilms of medical relevance. SIGNIFICANCE AND IMPACT OF THE STUDY: Boswellia spp. essential oils represent an interesting source of anti-microbial agents in the development of new strategies to prevent and treat biofilms.