Heat shock protein (Hsp) 70 and Hsp 40 are stress proteins that cooperate as chaperones in mammalian cells. The present study was designed to determine the expression levels of Hsp 70 and Hsp 40 in colorectal cancer by immunohistochemistry and Western blot analysis. Among 50 colorectal cancer tissues studied, 80% and 14% of tumors showed specific immunoreactivity to Hsp 70 and Hsp 40, respectively. Hsp 70 and Hsp 40 were overexpressed in cancer tissue samples compared with normal tissues, on both analytic sets. However, there were no significant correlations between their expression and various clinicopathological parameters of colorectal cancer. Hsp 70 and Hsp 40 may be tumor markers for colorectal cancer.