Of 63 99mTc-phosphate bone images in 49 patients with neuroblastoma, 41 were abnormal, 17 showed tracer uptake within the primary tumor, 29 showed evidence of skeletal metastatic disease, and 17 demonstrated renal/urinary tract involvement. The metastases were asymmetric in 24 patients and symmetrical in 9, in whom they involved the metaphyses and epiphyses of the long bones. Except for one patient with multiple "cold" areas, all metastases were seen as focal hyperactive regions. Eleven of 42 skeletal radiographic surveys were abnormal. The radionuclide study appears to be more accurate than skeletal radiography in estimating bone involvement in neuroblastoma. Primary tumor concentration of the tracer is almost pathognomonic of neural crest neoplasms in childhood.