Proposed federal regulations regarding clinical research require that institutional review boards determine whether a research project involving children is justified and, if so, whether the child's assent and parent's permission should be required before the child becomes a research subject. A key factor in the IRB's decision is assessment of the risk to the child from participation in the research. Since data on frequency of risks associated with many pediatric procedures that may be employed in clinical research is lacking, a survey of pediatric department chairmen and pediatric clinical research center directors was conducted to ascertain their opinions of the risks of some procedures at various ages of childhood. Although most of these procedures were thought to be of minimal or less than minimal risk, a few (certain types of venipuncture, arterial puncture, and gastric and intestinal intubation) were thought to pose greater than minimal risk, especially in young children. Respondents were also asked to indicate the criteria used to decide whether a child is capable of giving assent to participate in an experimental procedure. In the majority of institutions (73%), it appears that this decision is left to the clinical judgment of the investigator or a member of the research group.