Histiocytosis syndrome is not rare disease of undnown etiology, characterized by development of granulmatouslesions with histiocytic proliferation. Authors analyzed 22 cases, which had been confirmed as histiocytosissyndrome from 1971 to Feb. 1980 with special attention to 15 cases showing positive findings on radiologicalexaminations. The resuls are as follows. 1. Overall male to female ratio was abut 2:1. the majority were between 1and 7 years of age. 2. Skeletal system was involved in orders as follows: skull, pelvis, femur, rib, spine. 3.Four cases of pulmonary involvement were experienced. All cases had interstitial involvement with reticulonodulardensities on roentgenogram. 4. We had experienced a pituitary tumor, presumably localized histiocytic mass, in apatient with diabetes insipidus. 5. In long bone involvement, diaphysis or metaphysis was usually involved, but inone patient, lesions were extended into epiphysis. 6. One case of platyspondyly was found, with symmetricalcompression.