In this editorial we argue for the need for better research evidence on the prevalence of child mental health problems in minority ethnic groups, service utilisation among these groups and whether some service barriers are specific for certain groups. Without such evidence it is not possible to influence policy and practice so that evidence-based and appropriate services can be designed and offered to these populations. The terms ethnicity, race and migration are often imprecisely defined, and mental health needs and outcomes vary between immigrants from different generations. There is also a complex interplay between minority status and social class, with terms such as ethnicity being a proxy for multifaceted sociocultural and economic variables. However, we need to start collecting better data on children from minority ethnic groups so that these relationships can be understood, services tailored on the available evidence and ultimately better care delivered to this group of children.