OBJECTIVES: There is a huge burden of disease for childhood asthma and allergies. Evidence on migration as a potential risk factor for asthma and allergies is contradictory; therefore, we aimed at assessing the international evidence for the association between migration status and asthma and allergies. METHODS: We conducted a systematic review on asthma and allergies and immigration status in accordance with the guidelines set by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The search was conducted in the PubMed database in November 2012 and we chose broad string and MeSH terms in our search to include any definition of asthma and allergies, and migration status. From the total of 2737 unique hits identified through the search, 127 studies were selected for a full-text review. After reviewing full-text papers, 54 studies were selected for data extraction and synthesis. RESULTS: The prevalence of asthma and allergies in newly arrived immigrants appeared to be similar to prevalences found in their countries of origin. A longer stay in the host country or being a child of immigrant parents is associated with increasing adaption to the new environment, and therefore the prevalence of asthma and allergies over time converge with the prevalence in the non-immigrant host population. Comparisons between populations in their countries of origin and those that emigrated vary depending on their level of development; more developed countries show higher rates of asthma and allergies. CONCLUSIONS: Preliminary findings suggest a strong influence of the environment on the development of asthma and allergies. The prevalence of asthma is generally higher in second generation immigrants. With length of stay the prevalence of asthma and allergies increases steadily. Further analysis should assess homogeneity across studies and obtain pooled risk estimates of migration status as a risk factor for asthma and allergies.