A ‘one-size fits all’-approach does not fit all pediatric asthma patients. Current evidence suggests that in children with persistent asthma, ADRB2 genotype-guided treatment can improve treatment outcomes, yet this evidence is mainly derived from observational and genotype-stratified studies. Implementation of precision medicine-guided asthma treatment in clinical practice will only occur if randomized clinical trials can show that this approach will improve patient outcomes and is cost effective. In this paper, we will discuss why precision medicine trials are currently needed to improve childhood asthma management and present the rationale and design of the PUFFIN trial, that has been set up to address this need.