BACKGROUND Cancer is the second leading cause of death in children younger than 15 years. Although 5-year survival rates have increased dramatically for many childhood tumors, more than 100,000 person-years of life are lost to childhood cancer each year. The exact proportion of pediatric patients with cancer who receive care at centers that use up-to-date therapeutic protocols (such as those affiliated with the Childrens Cancer Group (CCG) or the Pediatric Oncology Group (POG) is unknown. METHODS Based on residence at the time of diagnosis, observed numbers of pediatric cancer cases seen by member institutions of the CCG and the POG in 1989 and 1990 were compared with the expected number of cases. Expected values were calculated from incidence rates obtained from the Surveillance, Epidemiology and End Results Program and population counts obtained from the US Census Bureau. RESULTS Results indicate that more than 90% of children younger than 15 years who have a diagnosis of malignant neoplasm are seen at an institution that is a member of either CCG or POG. The highest proportion seen occurs in the youngest (0-4 years) age group, and the proportion declines steadily with increasing age. CONCLUSIONS There are specific regions within the United States where the observed number of cases was substantially less than the expected number, including areas of Texas, Idaho, and Virginia. Although the exact reasons for these potential deficits are unknown, additional study of these areas is recommended.