Since 1943 we have had the unusual opportunity of examining the chest films of many individuals who had been exposed to beryllium compounds in the form of dust, with pulmonary changes consisting in a bilateral diffuse nodular infiltration. The majority of these persons were or had previously been employed in plants making electric and fluorescent lamps. A few were engaged in the manufacture of beryllium copper alloy. Occupational histories have strongly suggested beryllium as the probable offending agent, especially in those workers who handled the fluorescent powder or came into contact with dust containing beryllium. The late Dr. Leroy U. Gardner was intensely interested in the intriguing problem of detecting the agent responsible for the lung lesions in these patients. Among the possibilities which he had under suspicion and investigation, in addition to beryllium, were the diphtheroid, virus and fungus infections, sarcoidosis of unknown etiology, silicosis, and exposure to other elements such as phosphorus, zinc, manganese, and copper. While he was not prepared actually to condemn beryllium, he definitely felt that it was in some as yet unrecognized manner involved. It was on his suggestion, made several months before his death, that the roentgen study of these interesting and unusual cases was undertaken, with the purpose of describing the findings, attempting a correlation with the clinical course of the disease, and finally considering the differentiation from other similar pulmonary changes. Clinical Features The following is a brief summary of the clinical findings obtained from the abundant correspondence concerning 32 cases in Dr. Gardner's files. Four additional cases referred to Saranac Lake for thorough study, and described below, will be included in a subsequent clinical report by Dr. George Wright. Recently, Hardy and Tabershaw (11) adequately described the clinical manifestations of a group of patients, many of whose chest films we were privileged to review. The patients were preponderantly females, due to the higher ratio of females to males employed in the plants where most of the cases developed. The ages varied from twenty-one to forty-three years, with an average of twenty-nine years. The average duration of exposure was sixteen months. An interesting feature, as pointed out by Hardy and Tabershaw (11), is the delay in onset of symptoms. These appeared, or the first positive x-ray evidence was discovered, twenty-four months (average) following change of job or cessation from the supposedly hazardous operation. Dyspnea, cough, and weight loss were the most frequent symptoms; fatigue, lassitude, anorexia, and low-grade fever were also occasionally present. The physical findings were limited to impaired resonance of the chest and fine râles throughout the lungs. Cyanosis was present in several patients. There was no involvement of the peripheral nodes, nor any consistent enlargement of the liver or spleen.