Summary We tested the hypothesis that the increased incidence of schizophrenia among Surinamese immigrants to The Netherlands could be explained by a similarly high incidence in Surinam. We conducted a 1-year first-contact incidence study in Surinam and compared the findings with data from a similar study conducted in The Netherlands using the same inclusion criteria and instruments. The risk of developing a schizophrenic disorder was 2.4 times higher (95% CI 1.3–4.2) in Surinamese immigrants than in residents of Surinam. The increased risk is probably due to environmental factors in The Netherlands.

There is no satisfactory explanation for the increased incidence of schizophrenia among several immigrant groups to Europe (e.g. Cantor-Graae et al, 2003). Migration from the previous Dutch colony Surinam to The Netherlands is of particular research interest, because it was large-scale and relatively unselective. We therefore conducted a first-contact incidence study in Surinam to test the hypothesis that the increased incidence of schizophrenia among Surinamese immigrants could be explained by a similarly high incidence in Surinam. We used data from a study in The Netherlands, in which exactly the same inclusion criteria and instruments had been applied (Selten et al, 2001).