A 9-year-old girl with pulmonary alveolar microlithiasis is presented. She was asymptomatic except for failure to thrive. Plain chest radiographs on admission showed sand-like opacities with calcific densities throughout both lung fields. predominantly in the lower zones. A black pleural line was also seen between the ribs and lung parenchyma. High-resolution CT (HRCT) revealed diffuse ground-glass opacities throughout both lungs, micronodular densities. interlobular septal thickening, linear calcifications along the pleura and a few scattered subpleural cysts. Disodium editronate. which is known to inhibit the microcrystal growth of hydroxyapatite, was started at 10 mg/kg per day orally. After 1 year of therapy, considerable regression of the calcific densities was detected on chest radiographs and HRCT scans.