This note discusses the UK regulatory framework for mitochondrial replacement therapies and compares it to the US landscape. It focuses on the regulatory and ethical discussions in both countries to find some lessons for debates about editing human germ cells.The first section introduces some biological characteristics of mitochondria and their implications for mitochondrial diseases, medical interventions and ethical as well as regulatory questions. The second section discusses the regulatory pathway leading to the adoption of the UK 2015 regulations and the main features of the approved text. The third section considers the current regulatory landscape in the US. The fourth section discusses some regulatory and bioethical questions raised by Mitochondrial replacement therapies.