Although the exact mechanism is not clearly understood yet, there were examples of the uptake of radiopharmaceuticals to the soft tissue lesions with Technetium methylene diphosphonate bone scan. Recently, v,e experienced two cases of neuroblastoma of which prirnary sites were imaged with" Tc-MDP bone scan preoperatively and could rnake the diagnosis. So, we report here that "Tc-MDP bone scan is the reasonable method not on]y to find out the bone metastasis, but also to diagnose the neuroblastoina preoperatively.