In The Netherlands, as in many other countries, many studies have addressed the health situation of migrant groups. After a discussion on methodological pitfalls in migrant studies, the article reviews the most important results. The data show that there are differences in the health status and mortality patterns between migrant groups and the indigenous population. Most, but not all, of the differences are in disfavour of ethnic groups. Possible determinants of these differences are evident in socio/cultural, genetic and socio-economic factors. A model is presented that demonstrates the relation between these factors and health and disease. Implications for research and for health policy are discussed.