Objectives: To investigate the expression of caspase-8 and -10 in rectal adenoma, adenocarcinoma and the corresponding normal mucosa tissue, and to clarify the relationship between their expression and clinicopathological parameters of rectal cancer. Methods: The expression of caspase-8 and -10 was determined by real-time RT-PCR and immunohistochemistry in 36 rectal adenomas, 93 rectal cancers and 93 corresponding normal rectal mucosa samples. Results: Compared with normal mucosa, the mRNA expression of caspase-8 was higher in adenomas (p = 0.003), while that of caspase-10 was lower in adenomas (p = 0.035) and cancers (p = 0.001). Immunohistochemical results showed caspase-8 up-regulation in adenomas (p = 0.014), and caspase-10 down-regulation in adenomas (p = 0.034) and cancers (p < 0.001) compared with normal mucosa samples. Cancers with poor differentiation had lower caspase-10 mRNA and protein levels than those with better differentiation (p = 0.041 and p = 0.046, respectively). The protein expression of caspase-8 and -10 was in accordance with the mRNA expression (p = 0.043 and p = 0.018, respectively). Conclusions: Caspase-8 expression was up-regulated in rectal adenomas. Caspase-10 expression was down-regulated in both rectal adenomas and cancers, and was further related to differentiation. Caspase-8 and -10 may be involved in the pathogenesis of rectal cancer. Copyright © 2008 S. Karger AG.