PURPOSE: This study evaluated the 3-year safety and efficacy of microwave ablation (MWA) as an alternative to radiofrequency ablation in Korean patients with hepatocellular carcinoma (HCC). METHODS: In this prospective single-center study, 33 adults with a single HCC lesion (2-5 cm; Barcelona Clinic Liver Cancer stage A) were enrolled between December 2017 and May 2020. All underwent ultrasound-guided MWA using the NEUWAVE system. One patient did not complete post-treatment evaluation and two had protocol deviations, yielding a full analysis set of 30 patients and a safety analysis set of 33 patients. Study endpoints included technical success (TS), technique efficacy (TE), local tumor progression (LTP), overall survival (OS), and adverse events (AEs) over a 3-year follow-up period. RESULTS: All 33 patients were included in the safety analysis, while 30 were included in the efficacy analysis. Most patients were male (83.3%), with a median age of 64 years and a mean tumor size of 2.5±0.6 cm. Median follow-up was 36.2 months. TS and TE were achieved in all cases. The 3-year cumulative LTP rate was 7.3%, and the 3-year OS rate was 90.0%. Minor AEs occurred in 54.5% of patients, most commonly post-ablation pain and fever. Two patients (6.1%) experienced major AEs, including pyrexia and duodenal thermal injury. No procedure- or device-related deaths occurred. CONCLUSION: MWA appears to be a safe and effective treatment for early-stage HCC, demonstrating durable tumor control and a low incidence of major complications over 3 years.