Prognostic factors in patients with surgically-treated peripheral T1 (< or = 3 cm in greatest diameter) adenocarcinoma of the lung were analyzed in 45 cases. Statistical difference in survival was observed between stages I + II and III + IV (p < 0.05). However, neither sex, age, location of tumor, histological subtype, histological grade, tumor ploidy, nor presence of central fibrosis was of prognostic determinance. Our results suggest that only clinical stage is of prognostic importance in surgically-treated peripheral T1 adenocarcinoma of the lung.