Of 42 radionuclide bone scans in 35 children with neuroblastoma, 21 were abnormal for the presence of skeletal metastases. Of the 21 abnormal scans, 16 were corroborated by positive bone-marrow biopsy or clinical data. The false-negative and false-positive rates for bone scanning were 4.8% and 9.5%, respectively. Calcification of the primary tumor was seen on pretreatment computed tomographic (CT) scans in 24 (89%) of 27 cases, while only 13 (48%) of 27 were detectable by plain radiographs. Uptake of technetium-99m methylene diphosphate (99mTc-MDP) by the primary tumor occurred in 20 of 27 cases, but correlation between tumor uptake and calcification was not statistically significant. All children with markedly elevated urinary vanillylmandelic acid exhibited primary tumor uptake. Survival was not affected independently by primary tumor uptake.