Objective Multidrug resistance is a major barrier for most patients with oral squamous cell carcinoma. In this study, we investigated the difference of the expression of Raf-1 mRNA and protein between multidrug resistant (KBV) and sensitive (KB) human oral squamous carcinoma cells to explore the effect of Raf-1 on the multidrug resistance in the human oral squamous carcinoma. Methods The changes of the mRNA and protein levels of Raf-1 in both KBV cells and KB cells were determined by RT-PCR,Western blotting assay and immunofluorescent method. By MTT and flow cytometry (FCM), ICSUB>50/SUB> and apoptosis rates in both KBV and KB cells were detected. Results The findings indicated that expressions of Raf-1 mRNA and protein levels in KB cells were lower than those in KBV cells statistically (P<0.01). Immunofluorescent image showed that Raf-1 protein expression in KBV cells were much stronger than that in KB cells. The ICSUB>50/SUB> in KB cells was (21.33±2.25)μg/L and that in KBV cells was (352.68±12.36)μg/L.The resistance index (RI) was 16.5The apoptosis rate in KB cells was (98.8±1.2)% and that in KBV cells was (23.5±2.1)%.These results showed that differences in the chemosensitivity to VCR between KBV cells and KB cells were significant statistically (P<0.01). Conclusion