Mitochondrial diseases are a common but challenging group of genetic conditions. The involvement of both the nuclear and mitochondrial genome means that the inheritance pattern is complicated. Mitochondrial diseases affect many different organs and may present to a variety of different physicians including endocrinologists. The treatment of mitochondrial diseases is challenging with no curative treatment available for the majority of patients. It is important to give symptomatic treatment such as optimum management of diabetes and cardiac problems. In view of the absence of curative therapies for patients with mitochondrial disease, prevention of disease transmission is important for families. For those families with nuclear inherited mitochondrial disease the reproductive options are similar to those of other nuclear genetic conditions. For those families with mitochondrial DNA mutations it is much more challenging. Mitochondrial DNA is maternally inherited and is present in multiple copies. Whilst techniques such as chorionic villus biopsy and preimplantation genetic diagnosis are valuable to some families, others will not benefit from this technique. Mitochondrial donation is a new reproductive option for these families which involves the transfer of the nuclear genes from an oocyte or zygote of a women that carried the mitochondrial DNA mutation into an oocyte or zygote from a donor woman. Thus any child born would have the nuclear genes of both parents but the mitochondrial DNA from a donor.