The clinical features of 30 children with IV-S neuroblastoma have been reviewed. They were treated at 11 Italian pediatric institutions in the period 1970-1981. Patients with IV-S neuroblastoma comprise 6.1% of all the neuroblastoma cases observed during that period. The age at diagnosis ranged from birth to 11 months (mean, 3 months). The distribution of "primary" lesions was of interest. The adrenal gland was affected most often (57% of patients), but tumors of the chest and neck were also encountered. No specific "primary" lesion was identified in ten children. The most frequent site of widespread disease was the liver (87%). Neither the size of the "primary" tumor, nor the number or size of subcutaneous nodules was of prognostic significance. Unfavorable features were age less than 2 months and clinical signs of pulmonary, renal, or hepatic embarrassment. These data confirm the need for prompt intervention in the infant who is suffering from compression of these vital structures by the enlarged liver. Radiation therapy is to be preferred for this purpose, because of the often severe toxicity that is associated with chemotherapy in infants. One, and possibly two babies in this series died of chemotherapy-related complications.