We document the first reported instance of offspring adoption in a wild leopard (Panthera pardus) population and discuss the potential fitness benefits accrued by the biological and foster mothers. A 15-year-old female leopard adopted the 7-month-old male cub of her 9-year-old daughter and successfully raised him to independence. The behaviour was presumably motivated by kin selection as no reciprocal support was gained by the adoptive mother, she did not benefit from additional parental experience, and it was unlikely to be a case of reproductive error.