M. Tech. Pharmaceutical Sciences / Bacteria are present in natural environments and can develop into biofilms. Mucus-like extracellular matrix produced by biofilms provides protection to biofilm formers by inhibiting antimicrobial penetration and de-activating antimicrobial molecules, while allowing strong attachment onto surfaces. Biofilm development is associated with otitis media and cystic fibrosis. In this study, selected biofilm-formers implicated in otitis media and cystic fibrosis, Pseudomonas aeruginosa and Moraxella catarrhalis, were used to evaluate the effect of combinations of mucoactive substances and antibiotics against their biofilms. Microtiter-plate assay and optical density measurements were used to evaluate antimicrobial and antibiofilm activities. Confocal scanning laser microscopy was used to visualise the effect of selected treatments against biofilms.