A 66-year-old man, an ex-smoker, was referred to our hospital for slightly progressive respiratory symptoms of cough and dyspnea on exertion and chest abnormal shadow. Chest high-resolution computed tomography showed wide-ranging ground-glass attenuation and reticulation with lower lobe predominance. Bronchoalveolar lavage (BAL) fluid revealed a marked increase in lymphocytes (53.0%), and a surgical lung biopsy revealed a pattern of desquamative interstitial pneumonia (DIP) with hyperplasia of the lymphoid follicles. His serum was positive for anti-Ku and anti-SS-A antibodies, and he had signs (such as Raynaud's phenomenon, joint pain, and mechanic's hand) suspicious of connective tissue disease (CTD) although a definitive diagnosis of CTD had not been established. On the basis of the findings in our patient obtained from the serologic domain, BAL, and pathological examination, clinicians should consider the important correlation of DIP with CTD as well as with smoking.