A smoker presented with pleuritic chest pain and was found to have reticulonodular interstitial opacities on chest x-ray film. Open lung biopsy revealed changes consistent with histiocytosis X, a disease seen almost exclusively in smokers. Smoking cessation was recommended, and the patient complied. A chest x-ray film taken nearly three years later revealed complete resolution of the radiographic abnormalities. It is proposed that smoking cessation may be related to the improvement in this patient's chest x-ray film findings, and that it should be recommended for all patients with pulmonary histiocytosis X.