Conventional dosage forms often lead to wide swings in serum drug concentrations. Most of the drug content is released soon after administration, causing drug level in the body to rise rapidly, attain maximum concentration and then decline sharply. This sharp fluctuations often cause unacceptable side effects at the peaks, followed by inadequate therapy at the troughs. In the transdermal drug delivery system, drug is released at a constant rate and provides plasma concentration that remains constant over an extended period of time. In the present work, chitosan film has been used as rate controlling membrane for the transdermal drug delivery of an antiemetic drug, Ondansetron HCl. This book throws light on the preparation and evaluation of chitosan membrane as well as provides a new method for the preparation of chitosan gel.This book also, provides the way of fabrication and evaluation of transdermal patches utilising chitosan films which shows promising potential for use in the transdermal delivery of Ondansetron HCl.