Geological and geophysical mapping reveal prominent Precambrian faults in the Borås area of south-western Sweden. No difference of altitudes exists at present between upfaulted and downfaulted areas, as peneplanation subsequently occurred. The maps suggest the faults to be approximately vertical with slips of several thousand meters. They have a preferred NNE—SSW- orientation, which is a characteristic feature of lineaments in south-western Sweden. The development from fracture to lineament is due to subsequent Tertiary (and probably also Cretaceous) erosion. In areas which suffered less erosion during these periods, even major faults are but little reflected in the topography. It is suggested that the same type of faults contributed to the development of the Lake Vättern depression. Riphean-Vendian sediments were there protected from erosion by downfaulting in late Precambrian time. The general orientation of faults and rock lineation of this area is NNE—SSW. Postcambrian, probably Permian, faulting of NNE—SSW orientation has occurred as well, judging by several indications. Thus it would seem that the Precambrian faulting, which affected the Vättern area, was to a great extent overprinted, while a set of NNE—SSW Precambrian faults is preserved in the Borås area.