Introduction: Health problems in people with intellectual and developmental disability (IDD) are traditionally known to be common in adults of all age, with at least twice as many health problems in this group as the general ageing population. In addition, there is considerable international evidence indicating an earlier death for people with IDD compared to the general population, exacerbated by fragmentation in health care systems and resulting in poor coordination between various health care services (WHO, 2018). Methods: An evaluation was done in Sweden, to estimate the effectiveness of the health system integration for people with IDD, and quality of coordinated care by professional health care personnel who had a coordinating function. In a survey, 114 medically responsible nurses, operating in key positions in 109 municipalities throughout Sweden, were asked to assess quality of co‐ordination between various centres for social services and health‐care units for frail older people with IDD who in need of both social service and healthcare. Results: Results showed diverse coordinated care, ranging from very good to very poor cooperation between the nurses and various types of care and service units. Implications: The study findings emphasise the importance of effective coordinated care.