Purpose: Simple X-ray study and bone scan have limiitations for early diagnosis of bone or bone marrow lesions in multiple myeloma. The purpose of this study was to evaluate the diagnostic usefulness of bone marrow imrnunoscintigraphy using anti-granulocyte monoclonal antibody for the evaluation of bone involvement I:n multiple myeloma. Materials and Methods: In 22 patients (Male: 15, Female: 7) with multiple myeloma, we perforrned whole-body immunoscintigraphy using ' Tc-labelled antigranulocyte antibody (BW 250/183, Scintimum Granulozyt CIS, France) and compared the findings with those of simple bone radiography and " Tc-MDP bone scan. Abnonnal findings in bone marrow scintigraphy were, considered to be present in case of expansion of peripheral bone marrow or focal photan defect in axial bones. Results: Marrow expansion was noted in 15 of 22 patients (68%). Focal photon defects were found in 18 patients (82%). While one (33%) of 3 patients with Stage II disease showed focal defects in bone marrow scan, abnormal focal defects were observed in 17 of 19 (90%) patients with Stage III. Among 124 focal abnormal sites which were observed in bone marrow scan, bone scan or simple bone radiography, bone rnarrow scan detected 92 sites (74%), whereas 82 sites (66%) were observed in simple bone radiography(58 sites, 47%) or bone scan(40 sites, 32%). Fifty-one (41%) out of 124 bone lesions were detected by bone marrow scan only, and located mostly in thoracolumbar spine. Conclusion: Bone marrow scan using " Tc-labelled antigranulocyte antibody seems to be a more sensitive procedure for the detection of pathologic bone lesions than simple bone X-ray ar bone sean in patients with multiple myeloma. (Korean J Nucl Med 1998;32:354-64)