Abstract Context Growth hormone deficiency (GHD) in children is currently treated with daily injections of GH, which can be burdensome for patients and their parents/guardians. Somapacitan is a GH derivative in development for once-weekly treatment of GHD. Objective This work aimed to assess the efficacy and safety of somapacitan, and associated disease/treatment burden, after 4 years of treatment and 1 year after switching to somapacitan from daily GH. Methods This long-term safety extension of a multicenter, controlled phase 2 trial (NCT02616562) took place at 29 sites in 11 countries. Patients were prepubertal, GH-naive children with GHD. Fifty patients completed 4 years of treatment. Patients in the pooled group received somapacitan (0.04, 0.08, 0.16 mg/kg/week) for 1 year, followed by the highest dose (0.16 mg/kg/week) for 3 years. Patients in the switched group received daily GH 0.034 mg/kg/day for 3 years, then somapacitan 0.16 mg/kg/week for 1 year. Main outcome measures were height velocity (HV), change from baseline in HV SD score (SDS), change from baseline in height SDS, disease burden, and treatment burden for patients and parents/guardians. Results Changes from baseline in HV and HV SDS were similar and as expected in both groups. Observer-reported outcomes showed that patients and parents/guardians seem to have experienced a reduced treatment burden when switching from daily GH to somapacitan. Most parents/guardians (81.8%) strongly/very strongly preferred somapacitan over daily GH. Conclusions Somapacitan showed similar efficacy and safety in patients who continued somapacitan treatment and those who switched from daily GH to somapacitan. Once-weekly injections may lead to a reduced treatment burden relative to once-daily injections. A plain-language summary of this work is available.