In a first systematic study of Cretaceous ostracods from Antarctica, a middle to upper Campanian fauna from James Ross Island, Antarctic Peninsula, is described. Previously, the existence of these microfossils has only been mentioned in passing by a few authors. The material was sampled at Hamilton Point on the southeastern part of the island. The fauna contains a moderately rich and diverse association of marine ostracods, which are assigned to thirteen genera, including: Cytherella, Cytherelloidea, Bairdia, Bythocypris, Argilloecia?, Paracypris, Majungaella, Mandelstamia, Rostrocytheridea, Cytheropteron, and Eocytheropteron. In addition, Trachyleberididae gen. et sp. indet. and one indeterminate taxon occur. Among the sixteen species present, two are described as new: Mandelstamia antarctica n. sp. and Rostrocytheridea hamiltonensis n. sp.