BACKGROUND: Essential tremor (ET) is a common type of tremor. Previous research has shown that wearable orthoses and biomechanical loading methods can suppress tremors. OBJECTIVE: This study aims to investigate the effect of a harmonic liquid dampener on upper extremity ET. METHODS: The study involved 9 women and 5 men from a neurology outpatient clinic. A 285-g liquid-based harmonic dampening wristband was used. Tremors were recorded from the wrist along the x-y-z axes using a vibrometer, and the Bain-Findley Rating Scale (BFRS) was employed for assessment. RESULTS: BFRS scores significantly improved after the wristband was used (mean difference 35.64, P = 0.001, Cohen's d effect size =2.979). The tremor amplitude decreased significantly along the x-axis (Cohen's d: 1.35, P = 0.001), y-axis (Cohen's d: 3.232, P = 0.001), and z-axis (Cohen's d: 3.321, P = 0.001). CONCLUSION: The liquid-filled harmonic dampening wristband shows promise as a new, effective treatment option for ET patients. © 2025 International Parkinson and Movement Disorder Society.