Objectives: For patients with multiple small-sized pulmonary cancers, a lobectomy can disrupt future therapeutic options for other lesions. It was recently reported that limited pulmonary resections were not inferior to lobectomy for the management of selected peripheral small-sized pulmonary adenocarcinomas. Patients with adenocarcinoma in situ or minimally invasive adenocarcinoma, as proposed by the International Association for the Study of Cancer classification, have been reported to have 100% survival after 5 years. However, that classification can be applied postoperatively. Since 2005, we have been intentionally performing limited pulmonary resection procedures for small-sized adenocarcinoma cases based on intraoperative imprint cytological diagnosis and our classification (Nakayama-Higashiyama's classification). Materials and Methods: A total of 120 consecutive cases were included in this study. Lung tumors were removed intraoperatively by wedge resection, and stump smear cytology was performed, from which the cases were classified into 5 groups based on our classification. When the tumor was classified as Group I or II, the operation was finished. When diagnosed as a more advanced classification, a lobectomy and lymph node dissection were additionally performed. Results: The 5-year survival rate for Group I and II was 100%, while those for Group III and IV-V were 95.8% and 94.4%, respectively. The 5-year disease-free survival rates for Group I and Group II were 100% and 97.1%, respectively, and for Group III and IV-V they were 100% and 94.1%, respectively. Conclusion: Use of cytological findings along with Nakayama-Higashiyama's classification for determining operation procedure is effective for treatment of patients with small-sized pulmonary adenocarcinoma.