We have studied expression of tenascin (TN) in colonic carcinoma cells from 81 patients with colonic carcinoma without (20) and with (61) lymphogenous metastases, in order to assess whether TN plays a role in local invasiveness and metastasis of tumors. In metastatic colonic carcinoma tissues from 52 cases, moderate, partial expression of TN was observed in the primary foci but no TN expression was observed in tissues from 9 others. However, in every case of nonmetastatic colonic carcinoma, very strong TN expression was observed in the tissues. Furthermore, the presence of dense TN accumulation correlated well with the prognoses (1-year survival) of colonic cancer patients (p less than 0.01). Weak TN expression was observed in 24/61 of the metastatic lymph nodes examined. In 2 patients with metastatic colonic carcinoma, the colonic cancer cells produced TN. TN may, therefore, play a role in limiting or preventing local tumor invasion rather than preventing metastasis and is a useful marker for predicting the prognoses of patients with colonic cancer.