Background In the past decades, the ethnic diversity of the population in the Netherlands has rapidly grown. At present, approximately 10% of all people in the Netherlands belong to immigrant families that originate from a very large variety of non-Western nations. Although it is often assumed that migration has a stress-inducing effect, leading to heightened levels of mental health problems in both immigrant children and their parents, research into this group of children is very scarce in Europe. In this paper, we want to report on the mental health of immigrant children originating from non-Western countries enrolled in a large cohort study in the Netherlands. Method A large sample of 11-year-old children in the Netherlands (n = 2230) participated in the TRacking Adolescents' Individual Lives Survey ( TRAILS). Approximately 10% of these children ( n = 230) belong to immigrant families originating from non-Western countries. Mental health problems were assessed using self-report measures ( Youth Self-Report), using parent-report measures ( Child Behaviour Check List) and using teacher report ( Teacher Checklist for Psychopathology). In this paper, we report on the mental health problems of these children from all three perspectives ( child, parent, teacher). In analysing the impact of immigrant status, the effect of gender and of socio-economic inequality was taken into account. Results According to self-report measures, mean level of mental health problems in immigrant children is comparable to that in non-immigrant children. Immigrant parents report higher problem rates for their daughters, in particular for internalising problem behaviours, social problems and attention problems, but not for their sons. In contrast, teachers perceive higher levels of externalising problem behaviour, but lower levels of anxious/depressed problems, social problems and thought problems in immigrant children. This last effect is most strongly found with respect to boys: teachers perceive less withdrawn/depressed problems, ...