Data on the health status of migrants are still scarce. One of the reasons for this is that migration status has not been well recorded in official statistics and epidemiological studies. In order to obtain an adequate and standardised operationalisation of migrant status, we first need an exact definition of the terms "migrant" and "migration background". We discuss approaches to the definition of terms and the surveying of ethnic minorities and migrants, and then develop a basic set of migration status indicators for use in epidemiological research. This set of indicators includes country of birth of the father and mother, year of immigration, mother tongue, German language skills and status of residence. The key indicator for the identification of migrants is the country of birth of the parents and not the nationality as was previously often the case. Thus, the classification based on the judicial category of nationality is replaced by a classification based on the biographical event "migration". Migration brings with it specific life conditions and challenges that can impact health across several generations. An instrument for surveying migrant status must be further developed both to reflect the special conditions of the life situation resulting from the migration experience and to take as full account as possible of all aspects of a migrant's history.