Ultrastructures of 11 cases of neuroblastoma and ganglioneuroblastoma were observed. Ultrastructurally, the neuroblastoma could be classified into four types: immature, poorly differentiated, differentiated and ganglioneural cell. Neurosecretory granules (NSG) of round or oval shapes with various diameters in the tumor cells and neural processes were observed. The presence of NSG in the tumor tissue is one of the pathognomic features for neuroblastoma. Comparing and study of the relation between the ultrastructural findings and the excretory patterns of the urinary catecholamine as well as the prognosis, it was shown that the tumor of the differentiated type and the presence of abundant NSG lead to a good prognosis. Some slight differences in ultrastructure were found in neuroblastoma specimens from children of various ages. Infants under 18 months had a longer survival time, which is related to the differentiation and other features of the tumor cells.