The authors report 2 rare cases of non-Hodgkin's lymphoma accompanied by pulmonary involvement with diffuse ground-glass opacity in a 59-year-old man who was suffering from progressive dyspnoea for 2 months and a 74-year-old man who presented with a persistent dry cough and slight fever for 2 weeks. Histological examination of the lung revealed a rare occurrence of diffuse large B-cell-type lymphoma within the bronchiolar wall and alveolar septum. The authors suggest diffuse large B-cell-type non-Hodgkin's lymphoma be considered in the differential diagnosis of pulmonary diffuse ground-glass opacity in the chest computed tomography.