Teollisuuden Voima Oy (TVO) is preparing for the final disposal of spent uranium fuel from the Olkiluoto nuclear power plant deep in the Finnish bedrock. The report presents a summary of the geological conditions at Romuvaara in Kuhmo, which was one of the five areas selected in 1987 for the preliminary site investigations. The Romuvaara site and its surroundings belong to the Archaean basement complex, the age of the oldest parts of which is over 2800 Ma. The bedrock consists mainly of migmatic banded gneisses (tonalite, leucotonalite and mica gneiss). These rock types are intersected by granodiorite and metadiabase dykes. Proterozoic metadiabases represent the youngest rock unit in the area. Except for the metadiabase, the rocks have undergone a multiphase Archaean deformation. The bedrock structures are interpreted as representing six deformation phases, after which sharp faults developed during at least four further movement phases.