Chitosan has been investigated as an excipient in the pharmaceutical industry, to be used in direct tablet compression, as a tablet disintegrant, for the production of controlled release solid dosage forms or for the improvement of drug dissolution. Chitosan has, compared to traditional excipients, been shown to have superior characteristics and especially flexibility in its use. Furthermore, chitosan has been used for production of controlled release implant systems for delivery of hormones over extended periods of time. Lately, the transmucosal absorption promoting characteristics of chitosan has been exploited especially for nasal and oral delivery of polar drugs to include peptides and proteins and for vaccine delivery. These properties, together with the very safe toxicity profile, makes chitosan an exciting and promising excipient for the pharmaceutical industry for present and future applications.