CyberKnife radiation therapy has a widely used system in the treatment of extracranial lesions. Implanting gold fi ducial markers around a tumor is an important procedure for the planning and aiming of CyberKnife radiation therapy. Thus, the purpose of this study was to evaluate the feasibility, safety, and effi cacy of percutaneous fi ducial marker implantation of hepatic malignancies under sonographic guidance for CyberKnife radiation therapy. Materials and Methods: From April 2009 to November 2011, we retrospectively reviewed 30 percutaneous fi ducial marker implantations in 30 patients with hepatic tumors. All patients underwent percutaneous fi ducial marker implantation under sonographic guidance. The feasibility, safety, and effi cacy of this technique were analyzed on immediate follow-up unenhanced computed tomography (CT) and 1-week follow-up contrastenhanced CT. The effi cacy of this technique was defi ned as implantation enabling adequate treatment planning and CT simulation. Results: All 30 patients (100%) had successful fi ducial marker implantation under sonographic guidance. The mean number of fi ducial markers implanted per patient was 4.30 (range: 4-6 seeds). There was one minor complication (3.33%, 1/30). All 30 patients successfully underwent CyberKnife radiation therapy after fi ducial marker implantation. Conclusion: Sonographicguided percutaneous fi ducial marker implantation of hepatic malignancies is a feasible, safe, and effective technique for preparing patients before CyberKnife radiation therapy.