Using the reverse transcription PCR, we evaluated expression levels of various antigen presentation-related genes, including LMP2, LMP7, MECL-1, PA28 alpha, PA28 beta, TAP1, TAP2, and tapasin, in two oral squamous cell carcinoma cell lines, HSC5 and HSC7. Expression levels of LMP2, MECL-1, TAP1, and TAPS transcripts are reduced in both cell lines in comparison with a normal epithelial cell line. Further, HSC5 and HSC7 show diminished expression of LMP7/tapasin, and PA28 alpha/beta, respectively. Surface expression of HLA-B alleles is down-regulated in both lines presumably due to low expression of TAP1/2. However, HLA-A2 surface expression is not significantly down-regulated in HSC5 cells, suggesting an involvement of signal-sequence derived peptides in the TAP-independent pathway. The current study would contribute to our understanding of significance of abnormalities in the antigen presentation machinery of oral squamous cell carcinoma, and provide meaningful information in the design of CTL- based tumor vaccines by intra-cellular delivery system.