A new northern high-latitude Cretaceous-Tertiary (K-T) boundary section has been studied at Annertuneq on the north coast of Nuussuaq, West Greenland. The boundary section is situated in a succession of homogeneous dark mudstone deposited in a marine-slope environment. Identification of the boundary is based on the presence of the latest Maastrichtian palynomorphs Palynodinium grallator, Disphaerogena carposphaeropsis, Manumiella spp., and Wodehouseia quadrispina below the boundary and on the first occurrence of the earliest Danian species Senoniasphaera inornata above the boundary. Variations in sporomorph and dinoflagellate cyst abundances indicate latest Maastrichtian regression followed by early Danian transgression. The transgressive phase can be subdivided into three high-frequency transgressive-regressive cycles. Each cycle indicates upwelling and transgression, mixing with low-latitudinal water masses, and ocean conditions suggested by the peak occurrences of Senegalinium spp., Trithyrodinium fragile, and Spongodinium delitiense, respectively.