Forty-one confirmed cases of childhood neuroblastoma diagnosed over a 13-year period were reviewed and reclassified. Most of the tumors were stained using a peroxidase antiperoxidase method for neuron specific enolase (NSE), protein gene product (PGP) 9.5, and S100 protein, all of which have previously been reported to be positive in some neuroblastomas. The relation to prognosis of the histology and immunohistochemistry was studied. There was a significant trend toward improved survival with increasing degree of differentiation, and with decreasing mitosiskaryorrhexis index (MKI) in the stroma-poor group. There was no significant correlation between immunohistochemical staining and survival, although the presence and amount of staining for all three markers tended to increase with tumor differentiation. This study concludes that histologic classification in neuroblastoma is helpful in assessing prognosis but that the clinical features are generally more reliable as indicators of prognosis. The immunohistochemistry of markers used did not contribute towards assessment of prognosis.