Verbascum davidoffii Murb. (Scrophulariaceae), one of the rarest plant species in Bulgarian flora, is a local endemic, protected by the National Biodiversity Act, included in the Red List of vascular plants, as well as in the Red Data Book of Bulgaria with conservation status “Critically Endangered”. Its distribution is limited due to anthropogenic pressure, specific ecological requirements and low reproductive capability. In this study, we aimed to measure the genetic diversity level in the unique single world population of Verbascum davidoffii located in Pirin National Park, Bulgaria. We found high genetic diversity in the excitant population of the species. The present study indicates that the primary objective in conservation of Verbascum davidoffii is to preserve as much as possible of its evolutionary potential.