Congenital Adrenal Hyperplasia (CAH) describes a set of autosomal recessive diseases which affect enzymes mediating steroid biochemistry in the adrenal glands. In chromosomal females, the excess androgens associated with CAH cause virilization. Females with a high degree of virilisation can undergo feminizing genitoplasty in infancy or later in life. Parents and guardians are the medical proxies for their infants and therefore make decisions on their behalf. However, decision-making about feminizing genitoplasty can be very difficult. One tool that could help in such a situation is an electronic patient decision aid (PtDA). However, a PtDA for feminizing genitoplasty does not exist and there is insufficient information in existing literature to inform its design and development. Thus, the objectives of this study were to: (1) Identify user requirements, (2) Develop specifications for the design and development of the PtDA, and (3) Understand the best way to implement and distribute the PtDA We used the persona-scenario methodology to acquire user-requirements. Persona-scenario sessions were conducted with four parents of children with CAH, two adult patients with CAH, and four healthcare practitioners. Participants created fictitious personas, and scenarios wherein their personas interacted with an idealized version of the PtDA. Transcripts of these persona-scenarios and facilitator notes were analyzed to identify user-requirements, which were interpreted into specifications. Participants provided user requirements about (1) information and decisional content in the PtDA, (2) proposed functionalities for the PtDA, (3) web usability, and (4) implementation context. Many of these requirements are supported by existing literature. The requirements identified in this project will inform the design and development of a PtDA for feminizing genitoplasty in patients with CAH. However, further research is necessary to understand how to best implement these requirements and to ensure that the gathered information is useful for a broad range of potential end users. / Thesis / Master of Science (MSc)