Background: Transitioning from paediatric medical care to adult care is a challenging process for children, parents and healthcare professionals. The aim of this study was to explore the experiences, concerns and needs of parents of children with Down syndrome and of professionals regarding this transition. Method: A qualitative study was performed using semi-structured interviews with 20 parents of children with Down syndrome and six healthcare professionals. Results: We showed that parents and professionals have concerns during each of the three distinct phases of transition (preparation, transfer and integration). Data disclose specific concerns regarding communication, continuity of care and rebuilding trust. We propose a framework for the transition to adult care. Conclusions: The transition in medical care for children with Down syndrome should be flexible, patient-centred and coordinated together with patients and parents. Only in ensuring continuity of care will individuals with Down syndrome not get lost in transition.