In 1999, seven dark-bellied brent geese Branta bemicla bemicla were followed during spring migration from western Europe to Arctic Russia using satellite telemetry. For six of the birds we were also able to monitor their summer stay at the Taymyr Peninsula, and for five birds part of their autumn migration was recorded. In this article, we report on site use during summer and spring/autumn migration. We also describe migration routes and evaluate general migratory performance during autumn migration. All birds spent the summer within areas covered by the Great Arctic Reserve on the Taymyr Peninsula. None of the birds returned to the wintering area with young, so the sites used during summer were most likely used primarily for moulting. The birds remained at the same sites the whole summer until the start of autumn migration, indicating that the build-up of fuel stores for migration took place at the moulting sites. Autumn migration was conducted in a similar way as spring migration regarding routes and general migratory performance. Site use showed both a relatively large variation between individuals and seasons, as well as some degree of site fidelity as all birds returned for a longer stay in autumn to at least one of the areas they had used for more than two days in spring. Thus the migration of brent geese along the Arctic Ocean cannot be considered as a simple migration system with just a few key sites along the route, but instead it is a complex system with several localities used in different ways by different individuals. Most of the areas used by the satellite-tagged birds were previously known stopover areas, but some of them had not been recognised as being of importance for brent geese before. Most of the stopover areas do not have any kind of formal legal protection. It is suggested that further research should be carried out in the areas identified in this study to evaluate their importance and role in the migratory journeys of dark-bellied brent geese.