Abstract Disclosure: P.F. Backeljauw: Advisory Board Member; Self; Ascendis Pharma, Inc., Novo Nordisk, BioMarin. Consulting Fee; Self; Ascendis Pharma, Inc., Novo Nordisk, BioMarin, Cavalry, Upsher-Smith. Speaker; Self; Ascendis Pharma, Inc., BioMarin. A.K. Maniatis: Advisory Board Member; Self; Alexion Pharmaceuticals, Inc., Ascendis Pharma, Inc., BioMarin, Novo Nordisk, Pfizer, Inc.. Research Investigator; Self; Alexion Pharmaceuticals, Inc., Ascendis Pharma, Inc., OPKO, Novo Nordisk, Pfizer, Inc.. Speaker; Self; Alexion Pharmaceuticals, Inc., Ascendis Pharma, Inc., BioMarin, Novo Nordisk, Pfizer, Inc.. Other; Self; Alexion Pharmaceuticals, Inc., Ascendis Pharma, Inc., BioMarin, Novo Nordisk, Pfizer, Inc. M. Abuzzahab: Advisory Board Member; Self; Ascendis Pharma, Inc., Pfizer, Inc.. Consulting Fee; Self; Rhythm. Research Investigator; Self; Ascendis Pharma, Inc., Novo Nordisk, Lumos, Rhythm, Soleno, Medtronic, Inhale. Other; Self; DSMB for LG. S.D. Chernausek: Advisory Board Member; Self; Ascendis Pharma, Inc. T. Lipman: Speaker; Self; Novo Nordisk. A.K. Dewan: Advisory Board Member; Self; Pfizer, Novo Nordisk. Consulting Fee; Self; Novo Nordisk. Research Investigator; Self; Medtronic. Speaker; Self; Ascendis Pharma, Inc., Novo Nordisk. Other; Self; Twistle. G. Prakasam: Advisory Board Member; Self; Ascendis Pharma, Inc., Novo Nordisk, AstraZeneca, Johnson &Johnson, Lilly USA, LLC, Medtronic, Mannkind Corporation, Pfizer, Inc., Ultragenyx. Consulting Fee; Self; Ascendis Pharma, Inc., Novo Nordisk, AstraZeneca, Johnson &Johnson, Lilly USA, LLC, Medtronic, Mannkind Corporation, Pfizer, Inc., Ultragenyx. Grant Recipient; Self; Mannkind Corporation. Research Investigator; Self; Ascendis Pharma, Inc., Novo Nordisk, AstraZeneca, Johnson &Johnson, Lilly USA, LLC, Medtronic, Mannkind Corporation, Pfizer, Inc., Ultragenyx. Speaker; Self; Ascendis Pharma, Inc., Novo Nordisk, AstraZeneca, Johnson &Johnson, Lilly USA, LLC, Medtronic, Mannkind Corporation, Pfizer, Inc., Ultragenyx. Other; Self; Ultragenyx, Pfizer, Inc., Mannkind Corporation, Medtronic, Lilly USA, LLC, Johnson &Johnson, AstraZeneca, Novo Nordisk, Ascendis Pharma, Inc. M.B. Kabbani: Employee; Self; The Pediatric Endocrine & Diabetes Clinic, PC. E. Huang: Employee; Self; Ascendis Pharma, Inc. S. Raveendran: Employee; Self; Ascendis Pharma, Inc. C. Zhao: Employee; Self; Ascendis Pharma, Inc. J.N. Caminis: Employee; Self; Ascendis Pharma, Inc. A.D. Rogol: Advisory Board Member; Self; Ascendis Pharma, Inc., Tolmar. Consulting Fee; Self; Ascendis Pharma, Inc., Tolmar. Other; Self; United States Anti-doping Agency, World Anti-doping agency, Tomlar, Ascendis Pharma, Inc., Up To Date. Objectives: Lonapegsomatropin is a prodrug that delivers unmodified somatropin and is approved by the FDA and EC as a once-weekly treatment for pediatric growth hormone deficiency (pGHD). The overall objectives of the observational SkybriGHt study are to assess safety and effectiveness of lonapegsomatropin in the post-marketing setting. The primary objectives are to describe demographics, clinical characteristics, and treatment patterns. Secondary objectives are to describe clinical outcomes assessments (COAs), long-term outcomes of treatment, treatment adherence and persistence, and outcomes in patients transitioning from childhood to adulthood. Exploratory objectives will examine the impact of adherence on clinical outcomes, and assess all cause and GHD-related resource utilization and costs. A preliminary description of the baseline characteristics and demographics of the first 50 patients enrolled is described here. Methods: In the ongoing SkybriGHt study approximately 900 participants from the US, diagnosed with pGHD and prescribed lonapegsomatropin consistent with routine clinical practice, will be invited to enroll by their HCP. The decision to treat with lonapegsomatropin is made prior to and independently of any potential participation in the study. Participants are enrolled over a 5 year period with the study intended to conclude after 10 years. COAs are collected using questionnaires assessing health-related quality of life in functioning and well-being, treatment satisfaction, and patient preference. Safety is assessed via reporting of adverse events and laboratory test results. Results: Of the first 50 patients enrolled, 11 (22%) had participated in previous trials of lonapegsomatropin, 42 (84%) were male, the median age was 9.9 years (range 3.1, 15.0), and median age at diagnosis was 7.2 years. No participants were previously treated with long-acting GH prior to lonapegsomatropin, and 36 (72.0%) were treated previously with daily GH. Conclusions: The SkybriGHt registry will evaluate the long-term safety, effectiveness, and treatment use patterns (including demographics), with lonapegsomatropin in clinical practice. This preliminary baseline data show that patients were predominantly male, consistent with prior treatment patterns of GHD in the United States. Description of baseline characteristics of additional enrolled patients will be presented. Presentation: 6/3/2024