A total of 1,291 resected cases with primary lung cancers were used to demonstrate the differences of the result of surgical treatment between elderly cases 70 years old or more and non-elderly cases, and the results obtained herein were as follows: 1) Indication for surgery in elderly cases is considered to be similar with non-elderly cases, however, definite mediastinal lymphnode metastasis should be excluded. 2) Postoperative respiratory complications, which were often fatal, were significantly increasing in incidence with the advance of age. Per cent FVC, FEV1.0, SK/SD delayed type cutaneous hypersensitivity, operative bleeding volume and operative time are considered to be valuable predicted parameters. 3) Survival curve in elderly cases were significantly worse than that in non-elderly cases, however, there were no significant differences of survival rates between these 2 groups when cases dead within 3 months postoperatively were excluded. 4) Transfer factor is considered to be effective as an adjunct to surgical treatment in elderly cases. In conclusion, survival curve in elderly cases can be improved by deminishing respiratory complications and maintaining general condition with immunotherapeutics for long postoperative period.