A 37-year-old woman had worked for 4 years in a shell-processing factory where considerable airborne dust was produced cutting and polishing fresh water shells into pearl nuclei. She had a dry cough and dyspnea. Transbronchial lung biopsy showed noncaseating granulomas and cellular intraalveolar infiltrates. High-resolution lung computed tomography (HRCT) showed diffuse small nodules and ground-glass opacities. Hypersensitivity pneumonitis caused by shell dust should be considered in the appropriate clinical setting in a patient with the appropriate radiographic abnormalities.