Assessing medicines specifically for use in children has been neglected in the past, with the majority of formal clinical studies being conducted in adults. Clinical trials are a pivotal part of the drug approval process; however, they are not always applicable to the diverse populations - including children - that receive the drug after approval. They may not be the most informative assessment tool, especially in rare (or orphan) disorders where there are few patients, due to a lack of existing natural history data and the challenges of designing appropriately powered statistical analyses. Disease registries, which can collect clinical information in larger, more heterogeneous populations than can be included in a clinical trial, are becoming increasingly valuable. Their use is particularly beneficial for diseases affecting very small patient populations, such as lysosomal storage disorders (LSDs), and for looking at specific populations, for example, children. Such disease registries can provide natural history data as well as enable the impact of therapy to be examined. Moreover, despite potential limitations of enrollment bias and unmonitored data, patient registries can play a valuable role in assuring pediatric health, providing longitudinal data that can be used to monitor developmental outcomes in chronic lifelong diseases, and assessing the effectiveness of treatment. This review describes the role of registries in drug development and regulatory approval, the impact of global registry programs on pediatric research, with some examples from the field of LSDs, and how registries are impacting the clinical care such children receive.