Objective In the Netherlands, persons of Turkish, Moroccan and Surinamese descent form the largest groups of non‐western immigrants. A high prevalence of mild cognitive impairment (MCI) and dementia has been described in immigrant populations in the United States of America and the United Kingdom. We determined the prevalence of MCI and dementia in older community‐dwelling adults from the largest non‐western immigrant groups in the Netherlands. Methods Participants, aged 55 years and older, of Turkish, Moroccan (Arabic or Berber), Surinamese (Creole or Hindustani) or Dutch descent were recruited via their general practitioners. Cognitive deficits were assessed using the Cross‐Cultural Dementia screening instrument, which was validated in poorly educated people from different cultures. Differences in prevalence rates of MCI and dementia between the immigrant groups and a native Dutch group were analysed using chi‐square tests. Results We included 2254 participants. Their mean age was 65.0 years (standard deviation, 7.5), and 44.4% were male. The prevalence of MCI was 13.0% in Turkish, 10.1% in Moroccan–Arabic, 9.4% in Moroccan–Berber and 11.9% in Surinamese–Hindustani participants, compared to 5.9% in Surinamese–Creoles and 3.3% in native Dutch. The prevalence of dementia was 14.8% in Turkish, 12.2% in Moroccan Arabic, 11.3% in Moroccan Berber and 12.6% in Surinamese–Hindustani participants, compared to 4.0% in Surinamese–Creoles and 3.5% in native Dutch. Conclusions MCI and dementia were three to four times more prevalent in the majority of non‐western immigrant groups when compared to the native Dutch population. These differences are important for planning and improving healthcare facilities. Copyright © 2016 John Wiley & Sons, Ltd.