Palaeomagnetic sampling of the lower part of the Palaeocene flood basalts of West Greenland, covering a composite succession of 1.6 km and close to 350 individual lava flows, revealed two polarity zones and a 200-m zone of intermediate directions. 40 Ar/ 39 Ar ages indicate that the transition is C27n–C26r. Following palaeodirectional and rock magnetic analysis, 102 samples from 64 flows from the pre-transitional normal polarity zone, the zone of intermediate directions, and the post-transitional reverse polarity zone were chosen for Thellier palaeointensity experiments. Altogether, 83 samples yielded reliable palaeointensity estimates. The mean intensity of the pre-transitional C27n field is 16.1±6.9 μT (17 flows), which is only twice the mean transitional field strength, 9.9±3.7 μT (10 flows). The post-transitional C26r field intensity is generally high with a mean 43.3±15.0 μT (21 flows). The asymmetric palaeointensity around the C27n–C26r transition with a high post-transitional field resembles the only other detailed absolute palaeointensity studies of geomagnetic transitions recorded in volcanic sequences in Hawaii (∼4 Ma) and Steens Mountain (∼15.5 Ma). These new data, therefore, suggest that a strong post-transitional field might be a systematic feature of geomagnetic reversals, probably indicating a prolonged period of an unusual state of the geodynamo following polarity transitions.