Although essential for providing optimal adolescent patient support, knowledge of the impact of Marfan syndrome in adolescence is limited. To explore adolescents’ perceived impact of Marfan syndrome on (physical) functioning (activities, participation), disability (limitations, restrictions), contextual factors and support needs, we interviewed 19 adolescents with Marfan syndrome. Audio-recordings were transcribed, coded and analysed using thematic analysis. Identified themes were “difficulties in keeping up with peers” and “being and feeling different from peers”. Furthermore, an adolescent Marfan syndrome-specific International Classification of Functioning, Disability and Health for Children and Youth (ICF-CY) model derived from the data describing the adolescent perceived impact of Marfan syndrome on functioning, disability and its contextual factors. Adolescents perceived problems in keeping up with peers in school, sports, leisure and friendships/relationships, and they could not meet work requirements. Moreover, participants perceived to differ from peers due to their appearance and disability. Contextual factors: coping with Marfan syndrome, self-esteem/image, knowledge about Marfan syndrome, support from family/friends/teachers, ability to express needs and peer-group acceptation acted individually as barrier or facilitator for identified themes.