A stratigraphic study of the Rotliegend offshore Denmark has resulted in a coherent lithostratigraphic framework and a better understanding of the mid-Permian evolution of the eastern Northern Permian Basin. The Rotliegend Group is subdivided into the Karl Formation composed of syn-rift volcanics and volcaniclastic sediments, and the younger post-rift Auk Formation dominated by aeolian and fluvial sandstones. Radiometric age data based on K–Ar dating of plagioclase from the Karl Formation volcanics, combined with previously published age data suggests that volcanism took place during two separate events, 276–281 Ma and 261–269 Ma. Both events post-date the Lower Rotliegend volcanism (288–300 Ma) in the Southern Permian Basin, suggesting that the Northern Permian Basin was formed during a later tectonic event. The main volcanic event in the Northern Permian Basin was broadly coeval with volcanic activity in the Altmark area of NE Germany, reflecting simultaneous rifting and onset of Upper Rotliegend 2 sedimentation in the Northern and Southern Permian Basins.