Forty-six cases of resected lung cancer, including 20 cases at Stages I and II and 26 cases at Stage III (N2), were subdivided into two groups: a good prognosis group with a longer survival period and a poor prognosis group in which the patients died earlier of the cancer. From paraffin-embedded lymph node tissues of these patients, the authors examined DNA histogram pattern and DNA content, using flow cytometry, and histologic hyperplasia of germinal center and paracortical area; they also evaluated their correlation with the prognosis. In the good prognosis group at Stages I and II, paracortical hyperplasia (PH) of the lymph nodes was observed significantly more frequently. In the good prognosis group at Stage III, the incidence of PH, G2M phase in the DNA histograms, and DNA content were all significantly higher. DNA content was positively correlated with the grade of PH.