<b><i>Background:</i></b> Natural history (NH) studies, using observational methods, are common in rare and orphan diseases (80% of which have a genetic component). There is profound interest in identifying genetic mutations driving these diseases in these studies to support the formulation of targeted precision medicines. The global regulatory classification of NH studies with novel molecular biomarker collection has not been clearly delineated, presenting researchers with the challenge of determining how these studies are classified and regulated across multiple geographies. <b><i>Objective:</i></b> The aim of this investigation was to conduct a review of regulations related to NH studies and genetic testing to elucidate regulatory pathways to inform clinical researchers in the field. <b><i>Methods:</i></b> Regulatory provisions for NH studies and genetic testing were obtained from Pharmaceutical Product Development (PPD)’s propriety regulatory intelligence database and by surveying the company’s country-specific regulatory experts. A literature search was conducted in the Google Scholar search engine and PubMed for supplementary information. <b><i>Results:</i></b> Nineteen countries were evaluated; 37% classified NH studies with biomarker collection as noninterventional and 26% required regulatory approval (increasing to 47% when molecular biomarker testing was introduced). No regulatory provisions for genetic testing could be identified in 32% of countries, and 58% did not have binding requirements for genetic counseling. <b><i>Conclusion:</i></b> Lack of harmonization of regulations governing NH studies with molecular biomarker collection contributes to the operational complexity of conducting multinational studies in orphan and rare diseases. A set of harmonized international guidelines for these studies would improve efficiency, and this may be on the horizon with the recent adaption of International Conference on Harmonisation (ICH) guideline E18.