Early-onset Alzheimer's disease (EOAD) is an increasingly diagnosed condition and is associated with genetic risk factors. This is one of the first studies exploring the lived experience of siblings of individuals with EOAD. We used structured questionnaires and semi-structured interviews to assess a broad range of siblings' experiences with and beliefs about EOAD, including knowledge, perceptions of personal risk, level of worry, and effects on life decisions. Participants (n=24) were predominantly female (62.5%) and middle-aged (mean = 56.8 years; range 37–83). When asked about risk factors, genetics was cited most frequently (62.5%). Several potential means of reducing AD risk were endorsed, with 54% reporting engagement in behaviors for this purpose (e.g., keeping mentally active). Participants ranged widely in their perceived personal risk of AD (range: 0–100; mean = 35.6%), with higher perceived risk associated with worry about AD (p<0.01). Understanding siblings' experiences with EOAD can inform how genetic counselors and healthcare professionals work with this population to facilitate risk communication and decision-making about testing and healthcare.