Survival rates and several effective factors for the postoperative course of 10 advanced cases of small sized lung cancer (ASLC) were evaluated. Followings were considered as characteristics of these patients: 1) ASLC were observed at the rate of 4.0% of whole lung cancers, 2) ASLC were more often seen in relatively young patients, females and adeno carcinomas than ordinary lung cancer, 3) as factors concerned to postoperative prognosis, stage III A (especially T1N2M0), few numbers of metastatic lymph nodes in N2, and performance of relative curative operation may predict good prognosis, but adenosquamous type will be a sign of poor prognosis. Satisfactory result was obtained even in a case of stage IV when complete resection of metastasis was carried out. There was no significant difference of survivals between 2 cm and 3 cm of diameter of the tumor. In conclusion, above mentioned points should be considered when operative indication of ASLC is evaluated.