Background General practitioners (GPs) are increasingly confronted with people with both mild intellectual disability (MID) and mental health (MH) problems. Little is known about the type of MH problems for which people with MID visit their GP and the care provided.Objectives To identify the type and prevalence of MH disorders and MH-related complaints in people with MID in primary care and care provided, compared to people without ID.Methods By linking the Netherlands Institute for Health Services Research’s primary care databases, comprising electronic health records, with Statistic Netherlands’ social services and chronic care databases, we identified 11,887 people with MID. In this four-year retrospective study, MH-related International Classification of Primary Care (ICPC) codes and care characteristics were compared between people with MID and without ID.Results Of the people with MID, 48.8% had MH problems recorded vs. 30.4% of the people without ID, with significant differences in substance abuse, suicide attempts, and psychosis. Of the MID group, 80.3% were not registered by their GP with the ICPC code mental retardation. GPs provided more care to people with MID and MH problems than people without ID but with MH-problems regarding consultations (median 6.4 vs. 4.0 per year) and variety of prescribed medications (median 2.7 vs. 2.0 per year).Conclusion In primary care, the prevalence of MH problems and care provided is high in people with MID. To improve primary mental healthcare for this group, it is essential to increase GPs’ awareness and knowledge on the combination of MID and MH.