"Adenocarcinoma, mixed subtype" is the most common histologic subtype of lung adenocarcinomas in the World Health Organization classification of 2004. For small peripheral adenocarcinomas, for example, those measuring 2 cm or less in greatest diameter, invasive areas can present various histologic patterns. The purpose of this study is to present the radiologic features of small peripheral lung adenocarcinomas with or without a bronchioloalveolar component and with or without invasive areas, in comparison with histopathologic findings. For this purpose, a detailed evaluation of the characteristics of solid regions in ground-glass opacity on high-resolution computerized tomographic images of lung adenocarcinoma is useful.