To investigate the modifying effect of Kwao Kreu, Pueraria mirifica (PM), we performed two kind of studies which are the non-surgical medium-term carcinogenicity study and the modulation of gap functional intercellular communication study. The first study, a non-surgical medium-term carcinogenicity bioassay was done to investigate the modifying effect of Kwao Kent, Pueraria mirifica (PM), a rejuvenating folk medicine from Thailand, on the male F344 rat liver. Specific pathogen free, male 6-week-old F344 rats were divided into ten groups. To induce hepatocarcinogenesis, those in all groups were given a single i.p. injection of DEN (200 mg/kg) and were received two i.p. injection of DGA (300 mg/kg) at the ends of weeks 2 and 5. Rats of group 3-6 were given sodium phenobarbital (PB 0.05 % in drink). A diet containing 10 mg/kg PM was given to group 2 during the post-initiation phase and to groups 4 and 5 during promotion and initiation phase, respectively. Group 6 was given the experimental diet alone throughout the experiment (8 weeks). Rats of group 7, 8, 9 and 10 were fed 1000 mg/kg PM in the same manner as group 2, 4, 5 and 6. All animals were sacrificed at 8 weeks after DEN administration. Result of the iimmunohistochemical staining of the glutathione S-transferase placental form (GST-p) indicated that the numbers and areas of the preneoplastic leisions were not significantly changed in all PM treatment group comparing to control group. A.Iso the numbers and areas of GST-p positive foci among group 7, 8, 9 and 10 were not significantly changed in comparing to control group. To study the effect of PM on the modulation of gap functional intercellular communication, the present study was performed scrape-loading dye transfer (SL/DT) assay in human keratinocytes. The results showed that PM could not modulate GJIC. These results indicate that Pueraria mirifzca may have no carcinogenic effects on experimental hepatocarcinogenesis in rats and gap functional intercellular communication in human keratinocyte.