Two siblings, an eight-year-old girl and a three-year-old boy with lipid storage disease, most likely non-neuropathic Niemann-Pick disease (NPD) with sea-blue histiocytes, are presented. Both of them had foamy and sea-blue histiocytes in their bone marrow smears and reticulo-nodular appearance of both lungs on their chest X-rays. Case 1 had diffuse, biopsy-proven, pulmonary involvement associated with sea-blue histiocytes. Although diffuse reticulo-nodular pulmonary infiltration of non-neuropathic NPD (type B) is frequently detected on chest X-rays, to our knowledge there is only one reported adult case of lipidosis resembling NPD in which severe pulmonary involvement associated with pigmented histiocytes and Niemann-Pick cells were demonstrated at autopsy.