This paper describes the geochemistry of pre-3000 m.y. metadolerite (Ameralik) dykes from the well documented areas of Isua, Godthaabsfjord and Ameralik in West Greenland. The dykes fall conveniently into three divisions: (A) a more magnesian range of basaltic compositions having low K2O contents and flat REE patterns, (B) a less magnesian range of basaltic compositions with more fractionated trace element geochemistry, and (C) an ‘Ugpik’ group having compositions more consistent with the accumulation of pyroxenes in basaltic magma. Within Group A may be distinguished two minor variants, additional to the main group, one of which probably represents the influence of secondary processes.