Low medication-adherence and persistence may reduce the effectiveness of ADHD-medication. This preregistered systematic review (PROSPERO CRD42020218654) on medication-adherence and persistence in children and adolescents with ADHD focuses on clinically relevant questions and extends previous reviews by including additional studies. We included a total of n = 66 studies. There was a lack of consistency in the measurement of adherence/persistence between studies. Pooling the medication …