Chronic beryllium disease (CBD) is a rare disease characterized by diffuse interstitial pulmonary granulomatosis. We report a case of CBD which exhibited marked improvement both subjectively and objectively following pulse therapy. The patient was a 36-year-old man whose chief complaint was dyspnea and a dry cough. Since July 1990, the patient had been working in the development of an automatic or mechanical technique for producing beryllium-copper alloy. It appeared likely that the patient may have been exposed to metal beryllium fumes generated from an opening located just above the furnace. The Be concentration exceeded 25 microg/m3 transiently in the breathing zone in this workplace. A chest X-ray film taken in October 1994 showed fine granular shadows throughout the entire lung fields. Around August 1998, the patient's dyspnea became aggravated. An X-ray taken at that time showed linear and reticular shadows, in addition to the diffuse fine granular shadow. In October 1998, after 3 days of methylprednisolone pulse therapy, oral prednisolone 30 mg was initiated. With this treatment, the patient's pulmonary function tests and blood gases improved. Once the patient's condition had improved sufficiently, the dosage of prednisolone was decreased by 2.5 mg every two weeks. The patient continues to be monitored.