Immigrants from the third world are more prone to acquire nutritional deficiency diseases, such as rickets, osteomalacia and iron deficiency anemia than the rest of the population in the recipient countries. Lately, evidence is also emerging that some immigrant groups are particularly susceptible to diseases related to overnutrition, such as coronary heart disease and non-insulin dependent diabetes. The purpose of this review article is to give a holistic view of the nutrition related diseases and disorders among immigrants. It deals with the prevalence of these diseases among immigrants in Northern European countries, and looks into some of the hypotheses, which have been put forward to explain why immigrant groups are more prone to acquire these diseases than the rest of the population. The focus of this part of the paper is the process of dietary change after migration. The practical implications of the findings from the literature review are then discussed.