Background: While efgartigimod usage is expected to reduce immunoglobulin (IG) utilization, evidence in clinical practice is limited. Methods: In this retrospective cohort study, patients with gMG treated with efgartigimod for ≥1-year were identified from US medical/pharmacy claims data (April 2016-January 2024) and data from the My VYVGART Path patient support program (PSP). The number of IG courses during 1-year before and after efgartigimod initiation (index date) were evaluated. Patients with ≥6 annual IG courses were considered chronic IG users. Myasthenia Gravis Activities of Daily Living (MG-ADL) scores before and after index were obtained from the PSP where available. Descriptive statistics were used without adjustment for covariates. Results: 167 patients with ≥1 IG claim before index were included. Prior to efgartigimod initiation, the majority of patients (62%) received IG chronically. During the 1-year after index, the number of IG courses fell by 95% (pre: 1531, post: 75). 89% (n=149/167) of patients fully discontinued IG usage. Mean (SD) best-follow up MG-ADL scores were significantly reduced after index (8.0 [4.1] to 2.8 [2.1], P<0.05, n=73/167, 44%). Conclusions: Based on US claims, IG utilization was substantially reduced among patients who continued efgartigimod for ≥1-year, with patients demonstrating a favorable MG-ADL response.