The present study compares the reliability of MIBG and MDP bone scans in detecting bone metastases of neuroblastoma. Out of 57 patients, 23 had both 99mTc-MDP and 123I/131I-MIBG scans within a 2-week period. In 10 patients at primary diagnosis there was an underestimation of skeletal involvement by MIBG in 1/5, in 13 patients at follow-up in 3/9; 99mTc-MDP scans were able to visualize skeletal involvement in all those cases. There was only one false positive MDP scan. These results suggest that MIBG alone may fail to visualize skeletal involvement of neuroblastoma and should therefore be complemented by additional 99mTc-MDP scintigraphy.