The expression of T antigen in rectal cancer and mucosa remote from carcinoma by immunohistochemistry was investigated. Mucin protein was also examined by HID-AB staining. The results showed that the expression of T antigen in rectal cancer was much ber than those in 10cm mucosa remote from carcinoma and no significant difference as compared with 5cm mucosa. The sialomucin reactions in 5cm and 10cm mucosa remote from carcinoma were 45% and 20% respectively. The coincident sialomucin positive reaction and expression of T antigen were found in 40% 5cm remote mucosa .There is significant correlation between them (Ｐ＜0.05). The authors conclude that the expression of tumorrelated antigen and change of mucin protein in remote mucosa without malignant invasion may suggest the malignant potential of the mucosa. Further investigations should be performed into the effect of these changes on the local recurrence after redical resection of rectal cancer.