Seventy-one patients with neuroblastoma (NB) and 25 patients with other neoplastic or nonneoplastic diseases were studied with MIBG scintigraphy. Sensitivity and specificity at diagnosis were 94% and 88%, respectively. Of 52 patients with NB studied during follow-up, 14 had on one or several occasions conflicting results, when the findings at MIBG scintigraphy were compared to standard investigations (SI: CT scan, bone scan, x-ray, and ultrasound). The correlation of MIBG scintigraphy and SI to clinical outcome were in these 14 patients not significantly different. Adding VMA-excretion measurements did not significantly improve the predictive value of MIBG scintigraphy or SI. Patients with tumor-suspected lesions only at MIBG scintigraphy should be followed closely and the nature of the lesions should be explored through biopsy.