to investigate the role of the chinese herbal medicine xianhuayin on the reversal of 7,12-dimethylbenz[a]anthracene ( dmba)-induced premalignant mucosal lesions in the oral buccal pouch of golden hamsters . the animals were randomly divided into a non - diseased control group ( n=5 ) and an experimental group including 50 animals in which the buccal mucosa had been painted with dmba ( 0.5% in acetone ) to generate an oral mucosa premalignant lesion . animals in the experimental group were further divided into xianhuayin - treated group ( n=30 ) , untreated premalignant lesion group ( n=10 ) and normal saline ( ns)-treated group ( n=10 ) . the cheek ( buccal ) pouch mucosa of the golden hamsters in each group was observed with light and electron microscopy eight weeks after intragastric administration with ns or xianhuayin . in the non - diseased control group , the buccal mucosa was keratinized and stratified squamous epithelium under a light microscope . in the untreated premalignant lesion group , scanning electronic microscopic ( sem ) analysis showed that surface of the cells exhibited honeycomb structures in the hamster of untreated - group . the cells were morphologically irregular , overlapped and loosened in the untreated premalignant lesion group . transmission electronic microscopic ( tem ) analysis showed that buccal mucosal epithelial cells were morphologically regular in the non - diseased control group . desmosomes and tonofibrils were reduced and the nucleus was morphologically irregular in the untreated premalignant lesion group . in the xianhuayin - treated group , the widening intercellular gap was gradually reduced , desmosomes and the cells becoming morphologically regular . no significant difference was observed between the hamsters in ns - treated group and those in the untreated premalignant lesion group . xianhuayin is effective in the reversal of dmba - induced premalignant lesions in the buccal pouch of golden hamsters .