The possibility that Medicaid has encouraged pediatric emergency department (ED) use was explored as part of a study of 8470 ED visits to a pediatric teaching hospital in the period from 1975 to 1976. The proportion of the population on Aid to Dependent Children (proportion on ADC) was taken as a reasonable proxy for prevalence of Medicaid coverage of children in an area. Visit subgroups were compared using mean proportions on ADC in the census tracts of origin to measure relative rates of ED use by poor children If Medicaid has promoted use of the ED instead of other facilities, the data would be expected to indicate relatively heavy ED use by residents of tracts with a high prevalence of Medicaid: (1) during the week when other facilities are most available; and (2) for minor problems which do not result in admission. The data show no differences in the mean proportion on ADC in the census tracts of origin of ED visits on weekdays as compared to weekends or for visits which resulted in admission as compared with those which did not. The data challenge the idea that Medicaid has encouraged pediatric ED use.