OBJECTIVES: Patients with rare genetic diseases often experience a diagnostic odyssey; no diagnosis or a delay in obtaining a diagnosis, due to lengthy diagnostic work-ups. Whole-exome sequencing (WES) can rapidly identify the mutation(s) responsible for rare, single-gene diseases. Before incorporating this new technology into clinical practice, we must understand the value of diagnostic information. We aimed to identify key attributes surrounding the value of a diagnosis to develop a discrete choice experiment (DCE) survey to estimate the value of WES diagnostic information to parents of children with rare diseases. METHODS: We used a multi-phase, mixed-methods approach to identify key attributes and levels. We conducted a literature review to identify an extensive list of candidate attributes. We used results from focus groups with parents of children (n=15) and adults (n=8) with rare diseases to identify additional attributes. Candidate attributes were refined by consultation with research team members (including medical geneticists). The DCE survey was pre-tested in a sample of parents of children with rare diseases (n=5) and attributes were further refined.  RESULTS: The DCE included six attributes, each with four levels: type of diagnostic (genomic sequencing, other genetic testing, operative procedures, series of tests and procedures); chance of a diagnosis (1/10, 4/10, 6/10, 9/10); negative impact of diagnostic test results (lifestyle restrictions, victim of discrimination, labeled by others, no impact); positive impact of diagnostic test results (lead to therapy); out-of-pocket cost ($250, $1000, $5000, $10,000); time to obtain a diagnosis (6 months, 3 years, 5 years, 10 years).  CONCLUSIONS: The survey will be administered to n=300 parents of children with rare diseases (diagnosed and undiagnosed) to evaluate willingness-to-pay for: WES, a diagnosis, and a faster diagnosis.