The objective of this study was to investigate the in vivo bioadhesive properties of hydroxypropylcellulose (HPC) films containing seven polymer additives on the epidermis of 12 human subjects, including two ethnic sub-groups. HPC films containing polyethylene glycol (PEG 3350) alone, Vitamin E TPGS (TPGS) 5%, sodium starch glycolate 5%, Eudragit E-100 5%, carbomer 974P and 971P 5%, and polycarbophil 5%, all with and without plasticizer, were prepared by hot-melt extrusion utilizing a Randcastle Microtruder (Model #RCP-0750). Bioadhesion testing was performed using a Chatillon digital force gauge DFGS50 attached to a Chatillon TCD-200 motorized test stand to determine force of adhesion (FA), elongation at adhesive failure (EAF), and modulus of adhesion (MA) for the 12 films tested. In vivo, the TPGS-incorporated film exhibited a two-fold increase in FA when compared to the control film containing the PEG 3350 5%. The carbomer 971P and polycarbophil containing films were determined to have the highest FA and EAF, and the lowest MA of all films tested. The film containing carbomer 971P had a higher FA than the film containing 974P. In addition, films in one ethnic sub-group exhibited higher FA and EAF than the other. Force--deflection profiles obtained from these experiments indicate that the force of adhesion, elongation at adhesive failure and modulus of adhesion are a function of the polymer additive in the HPC extruded films. The incorporation of carbomer 971P and a polycarbophil into HPC films increased bioadhesion significantly when compared to the film containing HPC and PEG 3350. Differences in FA and EAF were discovered between two ethnic sub-groups tested.