Early field work on naked mole-rats, Heterocephalus glaber, suggested that small colonies are rare and that colonies can only form by fissioning of existing colonies. Many researchers expected that this would result in extreme inbreeding and high relatedness within colonies and would thus explain the evolution of eusociality in naked mole-rats. Here I report evidence of dispersers and outbreeding in colonies of wild naked mole-rats that suggests that inbreeding is not the system of mating for this species and that outbreeding is probably frequent. Wild dispersers have the same morphology as was reported for dispersers in laboratory colonies. Low levels of genetic variation in previous molecular genetic studies of naked mole-rats probably result from the viscous population structure typical of fossorial rodents.