Thirty samples from two sections on south-western Humps Island, James Ross Basin, northern Antarctic Peninsula, contain moderately diverse dinoflagellate cyst assemblages deposited in shallow shelf, open marine conditions. Assemblages contain common Isabelidinium spp., including I. cretaceum and I. pellucidum, Cerodinium diebelii, common Odontochitina spp., including O. operculata, O. porifera and O. spinosa, plus Nelsoniella cf. aceras, Octodinium askiniae and rare Chatangiella tripartita, C. victoriensis, Isabelidinium cf. belfastense and I. korojonense. This association includes species with Santonian and Campanian (to Maastrichtian) distribution in Australia and New Zealand. Some of these species may be recycled. A Campanian age is suggested for the Humps Island sections.