A 22-year-old woman was admitted with symptoms of dyspnea and fever with pulmonary infiltrates noted on her chest X-ray study. She developed these symptoms in the workplace; her job included the removal of body hair using a diode-laser with 1,1,1,2-tetrafluoroethane (HFC134a, an alternative to chlorofluorocarbon) as a coolant. A chest X-ray examination revealed ground-glass opacities in the lower lung fields, and a chest computed tomographic study showed diffuse centrilobular opacities. An examination of the bronchoalveolar lavage fluid revealed increased lymphocytes with a slight increase in the number of eosinophils. An examination of the transbronchial biopsy specimens revealed eosinophil infiltration. A peripheral blood eosinophilia was also seen. The patient's symptoms, chest X-ray findings, and arterial blood gas analysis all returned to normal within a week. A challenge test of 1,1,1,2-tetrafluoroethane (HFC134a) inhalation was performed, which resulted in an elevation of body temperature, the development of a cough, and laboratory data indicating increased inflammation. We then determined the patient's diagnosis to be extrinsic allergic alveolitis with eosinophil infiltration, caused by HFC134a.