an of various molecular weights, and microspheres made from several of its esters, were assessed for adhesiveness in vitro by means of detachment weight and mucociliary transport rate. Microspheres made from esters of alginic acid and gellan gum were also evaluated. The results were compared with those obtained from Carbopol 974 which was used as a positive control. Hyaluronan and its autocross-linked esters displayed comparable adhesion to Carbopol in both studies. All microsphere preparations were less adhesive than Carbopol (p < 0.05, Mann-Whitney U-test) when tested for detachment weight (using mucosal epithelium) and mucociliary transport rate. Adhesion to a mucus gel was similar for most preparations. Hyaluronan has been shown to possess excellent adhesion in vitro. Although formulation of hyaluronan into microspheres tends to reduce its inherent adhesive properties, the microspheres formed displayed significantly decreased mucociliary clearance. The inclusion of drug into such a biodegradable and biocompatible dosage form is an attractive prospect for transmucosal delivery.