Current innovation in pharmaceuticals determine the merits of mucoadhesive drug delivery system is particularly relevant than oral control release, for getting local systematic drugs distribution in GIT for a prolong period of time at a predetermined rate. The demerits relative with the oral drug delivery system is the extensive presystemic metabolism, degrade in acidic medium as a result insufficient absorption of the drugs. However parental drug delivery system may beat the downside related with oral drug delivery system but parental drug delivery system has significant expense, least patient compliance and supervision is required. By the buccal drug delivery system the medication are directly pass via into systemic circulation, easy administration without pain, brief enzymatic activity, less hepatic metabolism and excessive bioavailability. This review article is an outline of buccal dosage form, mechanism of mucoadhesion, in-vitro and in-vivo mucoadhesion testing technique.