When a new drug is approved in adults, the next question is to understand the drug’s efficacy in pediatrics. Even if in some cases that the pediatric clinical trials are not required, conducting well-controlled pediatric studies are usually encouraged . If disease manifestations and the drug’s effects are sufficiently similar between adults and the pediatrics, it is possible to extrapolate the adults’ efficacy findings to pediatrics’. However, it is not clear in what situations and degrees the extrapolation is appropriate. Collecting and summarizing trial information from the historical trials by indications will help us to shed light in answering this question. When efficacy data from an adult study cannot be extrapolated to the targeted group of pediatrics, adequately and well controlled clinical trials are required. The major challenges can be: 1) sample size determination in different age groups; and 2) dose determination 3) whether it is feasible to randomize patients in placebo. To tackle these challenges, innovative designs and statistical methods need to be considered. In this presentation, FDA experience and potential solutions in evaluating pediatric clinical trials will be discussed. Case examples in several disease areas such as gastroenterology and cancer will be shared.