Little is known about care needs of young adults with Fragile X Syndrome (FXS). Patient-driven information is needed to improve understanding and support of young adults with FXS. A qualitative study was performed in 5 young adult patients (aged 18–30), and 33 parents of young adults. Concerns and care needs were categorized using the International Classification of Functioning, Disability, and Health. Results indicated concerns on 14 domains for males, and 13 domains for females, including physical, psychological and socio-economical issues. In both groups parents reported high stress levels and a lack of knowledge of FXS in adult care providers. This study revealed concerns on various domains, requiring gender-specific, multidisciplinary transitional care and adult follow-up for patients with FXS.