An observational study of immigrant mortality differences in Norway by reason for migration, length of stay and characteristics of sending countries.

Independent of reason for migration and characteristics of sending countries, those who immigrate to Norway in adulthood appear to be particularly healthy. The higher death risk associated with prolonged lengths of stay suggests that disadvantageous 'acculturation' or stress factors related to the post-migration period may play a role in the long run. The health and welfare of long-term immigrants thus warrants further research.