The Indian rhinoceros (Rhinoceros unicornis) is a highly endangered species. It was be suggested that the Kaziranga and Chitwan populations are partially genetically incompatible. In this study, we compiled data from a captive population with data from Dudhwa National Park (India), where rhinoceroses were successfully reintroduced. In Dudhwa, the breeding male came from the Kaziranga population and four out of the five breeding females came from the Chitwan population. In spite of these different origins, the Dudhwa population has bred very well. From analyzing the influencing factors, it can be concluded that parity, not outbreeding, is responsible for infant mortality. The hybridization should help save the genetic diversity of this species.