An isopach map of the total sediment thickness over acoustic basement in the Norwegian-Greenland Sea is constructed on the basis of 44,000 km of seismic-reflection profiler data and available seismic-refraction information. The map shows a regional first-order deposition pattern that is believed to result from development of the ocean by sea-floor spreading. Where the pattern breaks down, the proximity to the continents governs the sediment distribution which also is locally complex. Most of the sediment in the Norwegian-Greenland Sea is suggested to be of terrigenous origin. Buried marginal basement highs exist in three locations near the base of the continental slope and have acted as barriers for the seaward flow of the terrigenous material during the early stage of development of the ocean. The oceanic basement surface is intersected by several fracture zones that are expressed as a linear series of basement peaks and sediment-filled troughs. The data are compatible with shifts of the active spreading axis south of the Jan Mayen Fracture Zone. An extinct ridge axis in the Norwegian Basin is defined by a continuous sediment-filled rift valley surrounded by partly buried axial mountains. A thick continuous sequence of relatively transparent sediments is located on the eastern rise of the Icelandic Plateau and on the northern flank of the Faeroe-Iceland Ridge; however, the prominent north-south trend in the bathymetry at the eastern boundary of the Icelandic Plateau is not reflected in the basement topography. Portions of the Icelandic Plateau are underlain by a smooth acoustic basement which is suggested to consist of volcanic debris. Erosion near the base of the continental slope and at the fracture zones may reflect bottom-water flow.