Leukemia, the most common malignant disease in the pediatric field, is one of the most interesting targets of modern medical research. So we reviewed the bone changes in 51 patients of leukemia admitted to the Dept. of Pediatrics Jeonbug National University Hospital for 5 years from Jan. 1st 1977 to Dec. 31st 1981. The results were as follow. The male patient was more prevalent with sex ratio male to female 2.7:1, and the highest incidence was noticed between 2 years and 4 years of age (23.5%) and followed by between 6 years and 8 years of age (21.6%). Acute lymphocytic leukemia occurred in 62.7%(32 cases) and acute myelocytic leukemia in 33.3%(17 cases), chronic myelocytic leukemia in 2%(1 case), acute monlcytic leukemia in 2%(1 case). The Most common symptoms and signs on admission was fever(56.9%), and followed y lymphadenopathy(52.9%), pallor(52.9%), hepatosplenomegaly(49.0%) in order of incidence. The most common chief complaint on admission was fever (39.2%), and followed by pallor(37.3%), and generalized malaise(25.5%). The patients with hemoglobin value under 4.0gm% occupied 21.6% and about two thirds showed hemoglobin less than 8.0gm%. The leukocyte counts on admission between 5, 000 and 1, 10, 000/㎣ was noticed in 6 cases (11.8%) and lower than 5, 000/㎣ in 8 cases(15.7%). In the chest X-ray the most common osseous change was metaphyseal band of humerus in 39.2%, osteolytic change in 31.4%, periosteal reaction in 7.8%, osteosclerosis in 2%. The most common extraosseous change in chest P-A was mediastinal widening with hilar lymphadenopathy in 31.4%, and followed by pulmonary infitration in 29.4%, pleural reaction in 5.9%. The twelve cases in which hematologic changes were mild, showed radiologic abnormalities in 10 cases(83%), and the 39 cases in which hematologic changes were severe, showed radiologic abnormalities in 31 cases(79%). Especially, in hematologic mild group, showed metaphyseal cortical scalloping of proximal humerus in 5 cases941%), and in hematologic severe group, showed metaphyseal cortical scalloping of proximal humerus in 15 cases(40%). So metaphyseal contical scalloping of proximal humerus may be the key finding on detection of early childhood leukemia. The osseous changes were notice in 75% of ALL, and 47% of AML, and the extraosseous changes were noticed in 60% of ALL, and 47% of AML.