Midface volume loss and contour deficiency are often treated using soft-tissue fillers capable of elevating and supporting facial features. To evaluate the effectiveness and safety of large gel particle hyaluronic acid with 0.3% lidocaine (LGP-HA-L) for the treatment of midface volume loss or contour deficiency. This 24-week, open-label study recruited adults aged 18 to 65 with bilateral moderate to substantial midface volume loss or contour deficiency (Medicis Midface Volume Scale (MMVS) score 3-4). The primary effectiveness measure was MMVS response (≥1-grade improvement) 8weeks after treatment according to evaluators blinded to injection volume. All enrolled patients (n=40; 85.0% female; mean±SD age 53.1±7.0 years) completed the study. Mean±SD injected volume for both sides of the midface was 5.3±2.5 mL. Week 8 MMVS response rates were 97.5% according to blinded evaluators and treating investigators and 90.0% according to patients; week 24 rates were 90.0%, 92.5%, and 82.5%, respectively. Global Aesthetic Improvement Scale response rates were 95.0% to 100.0% throughout the study. Adverse events were reported in 60.0% of patients and were mild or moderate; all resolved by study end and most within 1week. Midface volume loss or contour deficiency may be safely and effectively corrected using LGP-HA-L.