We examined immunohistochemically 111 cases of primary adenocarcinoma of the lung, for transforming growth factor alpha (TGF alpha) or epidermal growth factor (EGF), and argyrophilic nucleolar organizer regions (AgNORs). The presence of more than 75% positive cells for both growth factors was designated as a high-GF, while all others were considered to be a low-GF. If AgNORs counts were more than 5.00, it was considered to be a high-AgNORs group, while less than 5.00 was designated as a low-AgNORs group. In our 111 examined specimens, there were 51 (46%) cases of high-GF, and 64 (58%) with high AgNORs. The 5-year survival rates of the patients with a high-GF and low-GF were 34% and 57% (P < 0.05) respectively, while those with high-AgNORs and low-AgNORs were 21% and 81% (P < 0.001), respectively. In the cases of high-AgNORs, the 5-year survival rates of the patients with high-GF and low-GF were 0% and 36% (P < 0.05), respectively. However, in the cases of low-AgNORs, the 5-year survival rates of the patients with high-GF and low-GF were 83% and 79%, respectively. These data suggest that growth factors might be related to the biological malignancy of tumours with a high cell proliferation.