Background : It has been reported that younger patients with lung cancer have characteristic features that differ from those in older patients. The prognosis for young patients with this disease is controversial. This study aimed to determine the clinicopathological characteristics, the survival rate, and the risk factors associated with the overall survival rate in younger patients with lung cancer. Methods : The records of 120 young(age${leq}40$) patients with histologically confirmed lung cancer in the Korea Caneer Center Hospital(KCCH) between Jan. 1992 and Dec. 1998 were retrospectively reviewed. Of 5,082 lung cancer patients registered at the KCCH from 1992 to 1998, 120 older(age>40) patients were randomly selected as the controls. Results : More female patients(45.0% vs. 20.0%, p<0.001) and more adenocarcinoma cases(64.2% vs.38.3%, p<0.001) were found in the younger group, when compared to the older patients. In NSCLC, advanced disease(stage IIIB and IV) was more common in the younger patients(90.2%) than in the older patients(62.7%) (p<0.001). The Median survival was 8.6 months in the younger patients and 12.2 months in the older(p=0.003). In a multivariate analysis, only the advanced-stage was an independent negative prognostic factor. Conclusions : Lung cancer in the younger age group presents with a more advanced stage resulting in a poor survival rate, which suggests that lung cancer in this population is more aggressive than in older patients.