Development and validation of simplified renal clearance methods has required a research data base of multiple blood samples drawn over a substantial time interval, which is difficult to obtain for children. While the medical risks entailed in drawing multiple samples may be negligible, the problems of parental and institutional consent make such studies more difficult in the pediatric population. Scaling for patient size permits combining data from patients of different age and limits the number of studies required. A scaling technique is presented and evaluated here. With scaling, adult data can be used successfully to predict pediatric responses and to develop pediatric methods based on adult data alone. Inclusion of pediatric data improves the fit and permits development of generic methods that work with both adults and children.