In the Melville Bay area, offshore northwest Greenland, very large structures and sedimentary basins, which were predicted many years ago on the basis of magnetic and gravity data, have been confirmed by a recent reconnaissance seismic survey, with implications that are encouraging for petroleum exploration in the area. The Melville Bay area flanks a small ocean basin in Baffin Bay that is thought to have formed by oblique sea-floor spreading in the Eocene. There are two major, coast-parallel basins in the area. The inner basin, the Melville Bay Graben, is essentially a half graben with a maximum thickness of sediments exceeding 13 km. A complex fault-controlled ridge system separates this basin from the outer Kivioq Basin in which up to 7 km of sediments have accumulated. By analogy with onshore geology in the surrounding areas and well data from the continental shelves off southern west Greenland and Labrador to the south, it is expected that the first phase of rifting and sedimentation took place in the Early-middle Cretaceous, while a second phase of rifting took place in the latest Cretaceous and early Paleocene. Later, compression and inversion affected the northern part of the area, leading to the formation of large anticlinal structures. The existence of large tilted fault blocks and inversion anticlines provides grounds for anticipating the presence of large structural traps. Synrift sandstones and deeper water fans are expected to provide potential reservoirs, and correlatives of oil-prone source rocks known from the lower part of the upper Cenomanian-lower Maastrichtian Kanguk Formation in the Canadian Arctic may also have oil source properties in the Melville Bay area. Recent discoveries of live oil in the uppermost Cretaceous and lower Tertiary of onshore central west Greenland provide proof that oil has been generated in the region.