Niemann-Pick disease (NPD) is a rare, autosomal-recessively inherited lipid storage disease which is characterized by intracellular deposition of sphingomyelin in various body tissues. The disease is heterogeneous and classified into six groups. Pulmonary parenchymal involvement may be a feature of several subtypes of NPD, including type B. Progressive pulmonary involvement in NPD type B is a major cause of morbidity and mortality It is usually diagnosed at older ages. Only a few cases with early pulmonary involvement have been reported. In this report, a patient with NPD type B, hospitalized with the diagnosis of pneumonia at age 3 months, is presented. Following treatment for pneumonia, she continued to have persistent respiratory symptoms and became oxygen-dependent. High-resolution computed tomography of the chest revealed diffuse interstitial changes. During follow-up, the patient developed hepatosplenomegaly. Lung, liver, and bone marrow biopsies showed characteristic findings for NPD. Biochemical studies also confirmed the diagnosis, and the sphingomyelinase enzyme level of the patient was low. Unilateral lung lavage was performed in order to decrease lipid storage as a treatment modality However, there was no clinical or radiological improvement. The patient died at age 15 months due to progressive respiratory failure. Pulmonary involvement is a rare entity in early childhood in patients with NPD type B, but should be considered in the differential diagnosis of persistent interstitial lung disease. It may cause progressive respiratory failure, but the treatment options remain limited.