Abstract: Polymers and compositions, collectively “bioadhesive materials”, with improved bioadhesive properties have been developed. One or more compounds comprising: a) an aromatic moiety comprising two or more hydroxyl substituents, methoxy substituents, substituents hydrolyzable to hydroxyl substituents, or a combination thereof, and b) a primary or secondary amino moiety are either covalently attached to a polymer or are physically mixed with a polymer to form a bioadhesive material. These bioadhesive materials can be used, for example, to fabricate new drug delivery or diagnostic systems with increased residence time at tissue surfaces, and consequently increase the bioavailability of a drug or a diagnostic agent.