Topical delivery of antimicrobial agents is the most widely accepted approach aimed at prolonging active drug concentrations in the oral cavity. As most antifungals do not posses inherent ability to bind to the oral mucosa, this is best achieved through improved formulations. Chitosan, a partially deacetylated chitin, which is a biologically safe biopolymer, prolongs the adhesion time of oral gels and drug release from them. Chitosan also inhibits the adhesion of Candida albicans to human buccal cells and has antifungal activity. The antifungal agent, chlorhexidine gluconate (Chx), also reduces C. albicans adhesion to oral mucosal cells. The aim of this study was to design a formulation containing chitosan for local delivery of Chx to the oral cavity. Gels (at 1 or 2% concentration) or him forms of chitosan were prepared containing 0.1 or 0.2% Chx and their in vitro release properties were studied. The antifungal activity of chitosan itself as well as the various formulations containing Chx was also examined. Release of Chx from gels was maintained for 3 h. A prolonged release was observed with film formulations. No lag-time was observed in release of Chx from either gels or films. The highest antifungal activity was obtained with 2% chitosan gel containing 0.1% Chx. (C) 2000 Elsevier Science B.V. All rights reserved.