Flow cytometric DNA content analyses were performed on samples of 54 patients with neuroblastoma. DNA aneuploidy was detected in 55.6% of the 54 patients. A high incidence of DNA aneuploidy was observed in patients with prognostically favorable variables such as age (less than 1 year), clinical stage (I, II, or IVs), and primary site (extraadrenal sites). DNA aneuploidy was predominant in surviving patients, even in those with unfavorable variables. In patients 1 year old or more, the survival rate among those with DNA aneuploidy was 58.8% compared with 28.6% in patients with diploidy. Likewise, in patients with advanced stage (III or IV) neuroblastoma, the survival rate among those with DNA aneuploidy was 63.2% compared with 30.4% in patients with DNA diploidy. It is concluded that DNA content analysis is of value in predicting the prognosis of patients with neuroblastoma.