The aim of this PhD project was to increase knowledge, using population-based registers, of how pre- and post-migration factors and social determinants of health are associated with inequalities in poor mental health and mortality among refugees and other immigrants to Sweden. Study I and II had cross-sectional designs and used logistic regression analysis to study differences in poor mental health (measured with prescribed psychotropic drugs purchased) between refugee and non-refugee immigrants. In Study I, there was a significant difference in poor mental health between female refugees and non-refugees (OR=1.27; CI=1.15–1.40) when adjusted for socio-economic factors. In Study II, refugees of most origins had a higher likelihood of poor mental health than non-refugees of the same origin. Study III and IV had cohort designs and used Cox regression analysis. Study III analysed mortality rates among non-labour immigrants. Male refugees had higher relative risks of mortality from cardiovascular disease (HR=1.53; CI=1.04–2.24) and external causes (HR=1.59; CI=1.01–2.50) than male non-refugees did, adjusted for socio-economic factors. Study IV included the population with a strong connection to the labour market in 1999 to analyse the relative risk of hospitalisation due to depressive disorder following unemployment. The lowest relative risk was found among employed Swedish-born men and the highest among foreign-born females who lost employment during follow-up (HR=3.47; CI=3.02–3.98). Immigrants, and particularly refugees, have poorer mental health than native Swedes. Refugee men have a higher relative mortality risk for cardiovascular disease and external causes of death than do non-refugees. The relative risk of hospitalisation due to depressive disorder following unemployment was highest among immigrant women. To promote mental health and reduce mortality among immigrants, it is important to consider pre- and post-migration factors and the general social determinants of health.