Objective To analyze the characteristic of atypical adenomatous hyperplasia (AAH) in lungs though its computerized tomogaphy (CT) scan, pathology and surgical mode. Methods The investigators retrospectively evaluated 10 atypical adenomatous hyperplasias (AAH) that were histologically confirmed and that manifested pure ground glass opacity (GGO) on thin-section helical CT scans. There were 2 males and 8 females with a median age 54. 4 years old. All patients had the surgery. Their characteristic of CT scan and pathology were compared. All received a follow-up. Results In all cases,peripheral nodules were located at left upper lobe (n =4), left lower lobe (n =2) and right lower lobe (n =4). GGO at a diameter of 0.5 -1.2 cm was manifested on thin-section helical CT scans. The borderline of GGO was distinct and there was an equal density. Two of 10 cases underwent a wedge resection and 8 lobectomy. Postoperative patients recovered quickly without severe complications. Microscopically it manifested an apparent local pattern of alveolus epithelium hyperplasia in lungs. The alveolar interval had a slight increase. Local hyperplasia of fibrous cells was present with a slight degree of nucleus heteromorphism. The follow-up period was 2 months to 5 years. Ten patients with an excellent life quality survive without recurrence and metastasis. Conclusion The preoperative diagnostic rate of AAH is boosted by high-differentiation enhancement CT scan and CT number histograms. But a definite diagnosis still requires the histological evidence. Surgery is one of the most reliable therapy for AAH.