Tenascin expression was determined by an immunohistochemical technique in 120 surgical specimens of gastric carcinoma to investigate its relationship with clinicopathological factors. Tenascin expression was more prominent in the neoplastic area than in the adjacent nonneoplastic mucosa. Tenascin was frequently observed in gastric mucosa with diffuse chronic gastritis, glandular atrophy and intestinal metaplasia. In the neoplastic area, tenascin expression was positive in 72 cases (60 per cent). Tumours with a high frequency of tenascin expression included: Borrmann type II (19 of 20), well or moderately differentiated tumours (52 of 63), tumours with expansive growth and with an intermediate growth pattern (40 of 42), and those with a medullary or intermediate-type stroma (55 of 73). There was no significant relationship between tenascin expression and age, sex, depth of invasion, lymph node metastasis, invasion to lymphatic vessel, venous invasion and the 4-year survival rate.