OBJECTIVES: To understand the burden of GHD injection regimen and evaluate patient understanding of and ability to respond to newly developed questionnaires assessing human growth hormone (hGH) injection regimen burden. METHODS: A review of the empirical literature identified concepts relevant to hGH injection burden, with a focus on treatment regimen. Results informed the conceptual framework and two questionnaire batteries were designed to assess aspects of the treatment burden relating to using hGH injection in adult and pediatric patients. Expert advice meetings were conducted to confirm key measurement concepts and gather feedback on the questionnaires. Individual hybrid concept elicitation (CE) and cognitive debriefing (CD) interviews were conducted with patients (and caregivers of pediatric patients) to explore and confirm injection treatment burden concepts important to patients and caregivers, and to evaluate comprehensiveness of the questionnaires and respondents’ ability to understand and respond to the questionnaire instructions and items. RESULTS:  Results from the literature review (N=30 articles) and input from US (n=3) and European (n=3) experts facilitated the generation of questionnaire content assessing: (1) pen ease of use; (2) regimen convenience; (3) patient, caregiver, and family life interference due to regimen; (4) benefit/satisfaction/willingness to continue treatment; (5) regimen choice/preference; (6) intent to comply with regimen; (7) injection-related signs/symptoms; and (8) reasons for missed injections. Hybrid interviews with 21 patients (adults [n=6] and child/parent dyads [n=15]) confirmed that the questionnaires comprehensively capture their hGH injection-related treatment regimen experience (including key concepts), and are easily understood. Minor wording revisions improved question clarity and understanding of the concept. CONCLUSIONS: Findings from this research support the content validity of the questionnaires; resulting in new clinical outcome assessment measures to assess hGH injection regimen burden for adults, children and their caregivers.