To date, implementation of precision medicine for children has been limited. Extrapolation of adult experience streamlines pediatric drug development programs, and physiologically based pharmacokinetic models aid pediatric dose selection on a population basis. To achieve clinically viable individualization of drug therapy, genotype-stratified pharmacokinetic studies can efficiently characterize the extremes of the dose-exposure relationship. Reducing variability in exposure through genotype-based dosing may improve identification of genetic factors contributing to response, ultimately improving drug therapy for children.