Migration means that both locally and globally our world is getting more and more multicultural. From 1975 up to the year 2000, the number of migrants in the world doubled to 175 million, which is 3% of the world's population--half of them living in low-income countries . This figure includes labour migrants, permanent migrants, refugees, and asylum seekers, while undocumented migrants and people who migrate from rural to urban areas are not included. The increasing diversity of the population means new challenges for our societies, including our health services. The aim of this article is to outline a general framework for understanding the access that migrants have to healthcare and the factors that can affect that access.