Whether the DNA index (DNAI) of tumor cells and serum carcinoembryonic antigen (CEA) may be used to make prognosis in 78 patients with epidermoid lung cancer at the stage of T1-3 N(o) Mo was studied. There was a direct correlation between tumor ploidy and CEA levels. The two-year relapse- free survival among the operated-on patients at the stage T1-2 N(o) Mo was not shown to be associated with DNAI. At the same time in the T1-3 M1-2 Mo patients radically operated on, the two-year survival correlates with DNAI: it is significantly (p < 0,05) higher in patients with diploid tumors (DNAI = 1.0) than in those with aneuploid cancer (DNAI > 1.05). The patients with low preoperative CEA levels ( < 10 micrograms/l) have a more favourable prognosis after radical surgical treatment.