The common marmoset (Callithrix jacchus) is a non-endangered New World primate that is native to Brazil. Marmosets offer many advantages compared with other laboratory primates for studying reproductive biology: they are the only anthropoid primates that routinely ovulate multiple oocytes per ovarian cycle, have a short gestation period and reach sexual maturity at around 1 year of age. Moreover, it is possible to synchronize the ovarian cycle, and efficient protocols for superovulation have been developed over the last few decades. As this species is increasingly used in reproductive technology, basic technologies have been established to rival those available in Old World primates. In 2005, common marmoset embryonic stem (ES) cell lines were established and applied to several differentiation studies, which accelerated the development of regenerative therapies using human ES cells, and to the production of transgenic animals for human disease. With the recent development of induced pluripotent stem cells (iPS), non-human primate models using ES cells and iPS cells are needed for elucidation of the safety and efficacy of new technologies in regenerative medicine. In addition to their natural advantages as a model of humans, marmosets are also advantageous as experimental animals, and this should lead to a surge of interest among biological researchers.