Understanding the effects of habitat structure on otter (Lutra lutra) movements is critical to conservation management, but such information is scarce for riverine habitats where the species is most vulnerable. Between 1987 and 1990 the patterns of habitat use by five otters from river catchments in north-east Scotland were examined by using radio-telemetry. The main habitat variables analysed were channel width, substrate size, riparian vegetation, proximity to roads and buildings, and the coverage of surrounding vegetation and land use. All of the otters spent more of their time in relatively wide sections of river or stream, with high boulder cover and many riparian trees. However, when use was calculated as the time spent per unit area of water, narrow, gravelly streams were selected by most animals. Some of the habitat features traditionally thought to influence otter movements (e.g. riparian vegetation, land use) did not show the predicted effects. The conservation implications of these observations are discussed.