Pulmonary alveolar microlithiasis (PAM) is a rare disease with alveolar microliths mainly composed of calcium phosphate. The gene responsible for the disease is SLC34A2, which encodes a type-lib sodium phosphate cotransporter, has been described recently. Treatment of this disease is not clearly defined. Disodium etidronate is a member of bisphonates and it has been administered in these patients due to its inhibitory effect on the precipitation of hydroxyapatite microcrystals. Here, clinical and radiological improvement of two patients with PAM who were treated with disodium etidronate for 9 and 11 years, respectively, are presented. The pathogenetic mechanism of this treatment on the genetic basis of disease is discussed. Pediatr Pulmonol. 2010; 45:514-517. (C) 2010 Wiley-Liss, Inc.