Aim 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. Methodology 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. Results 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, variable degrees of epithelial dysplasia was observed. The irregular epithelial mucosa gradually became distinct in the Xianhuayin-treated 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. Most of the cell surface exhibited honeycomb structure in the Xianhuayin-treated 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. Significant therapeutic efficacy was observed in the group receiving Xianhuayin. Conclusion Xianhuayin is effective in the reversal of DMBA-induced premalignant lesions in the buccal pouch of golden hamsters.