Introduction: The pediatric-adult care transition, which takes place during adolescence, is a high-risk period for medical care adherence in chronic diseases, this encompasses treatment adherence, attending medical consultations and following healthcare advice. Studying perceptions is needed to get a more comprehensive picture of this care transition and to propose interventions to address the gaps. The authors analyzed perceptions from patients and caregivers in adolescents with sickle cell disease. Although this is the first step to improving the actual care management, to our knowledge, no study has explored perceptions from healthcare providers and compared it to patients' perceptions. The purpose of this study was to provide an insight on the experience of adolescent and adult patients, pediatric and adult healthcare providers in the context of pediatric to adult care transition, and analyze those concerns in order to better understand medical care adherence and improve patient care. Material and methods: Semi-structured interviews were conducted with adolescent and adult patients, as well as healthcare professionals (HCPs) in pediatric and adult departments. These interviews were audiotaped and transcribed before manual inductive content analysis. Results: A total of 15 adolescent patients, 10 adult patients, 9 pediatric HCPs and 13 adult HCPs - including 12 nurses - were interviewed. Patients and healthcare providers all agreed that the pediatric-adult care transition was poorly experienced. This was mainly due to various changes in habits, physicians, and care organization. Anticipating this transition and acquiring new skills both for patients and HCPs are essential steps for improving medical care adherence during this challenging pediatric-adult care transition. Conclusion: Propositions emerged from patients and healthcare providers to improve care and subsequently to improve medical care adherence in patients with sickle cell disease during and after the pediatric to adult care transition.